Manufacturing of HF antennas. Simple home-made receiving antennas for the ranges of DV, SV, HF waves. Gp to low frequency bands

When designing and operating your “antenna field”, you have to constantly maneuver on a tiny patch of roof between elevator booths, ventilation shafts, all kinds of television, satellite and other antennas, various cable communications, open broadcasting wiring ... In addition, one should take into account the very harmful all-weather " harvesting campaign 🙂 and dangerous natural phenomena - storm wind squalls, thunderstorm activity. And what about, say, icing ... By the way, in the winter of 2011, many radio amateurs in central Russia encountered this. It only takes one more or less long rain with a "minus" - even without wind - and then your beautiful antenna, a subject of former pride, right before your eyes turns into a shapeless icy lump of twisted scrap metal, fiberglass fragments and wire scraps!

Probably, raids by representatives of the native public utilities, as well as other "authorities in power" should also be attributed to the elements. First of all, of course, this applies to shortwaves living in standard high-rise buildings.

The number of happy owners of capital and reliable superantennas is growing steadily, but so far not as high as we would like. First of all, capital is usually spent on the purchase of a “bourgeois apparatus”, and there is no longer enough money to buy a branded antenna ...

What then remains to be done by the average domestic radio amateur, who often has practically no free access to the roof of his house? But you want to work on the world air, and even preferably not just anyhow, but with the maximum possible efficiency.

So, various cheap alternatives are invented (“needless invention!”) ​​Various cheap alternative options: window and balcony mini-structures, antennas “for emergency work”, 🙂 “invisible”, “reserve”, “disposable” - almost from thin copper wiring, "on buttons", as in the era of "spy fifth category" ...

Choosing the optimal antenna based on a wide variety of shapes and parameters, as well as specific local conditions, is not always easy enough. Everyone knows that "a good antenna is a better amplifier". Alas, not everyone can afford to have more than one antenna, and even several for each band is a dream ... Some people are forced to refuse to work, say, on the 80 m band adjacent to 7 MHz, just because "Inverted" has too high SWR there. However, unfortunately, it also happens that almost no attention is paid to matching the transceiver with the antenna. Personally, I myself know a rather curious case when one shortwave, having replaced an old home-made “Lapovka” with an imported device, “hooked” it to the usual “rope”, naively believing that “there is also protection for the output transistors ...”.

The literature has repeatedly described "antennas of a poor radio amateur", but all of them are far from the simplest and not at all cheap designs. Unfortunately, sometimes, due to an oversight of the authors of the descriptions, it happens that certain important details are overlooked - for example, the length of a two-wire line or the material of the mast, which is sometimes unacceptable to be made of metal. This makes it difficult for inexperienced colleagues to repeat the design.

Beginners (and, to be honest, also some “finishing”, 🙂) radio amateurs mainly use the simplest antennas - the “Delta Loop” of the 80m range (besides, it often has an unfortunate location and is powered as it was more convenient in place), The "notorious" Inverted V and the quarter-wave Ground Plane ... To work on other bands (and preferably on all!) One or another matching device can be used. In this case, the results of the antenna operation, depending on the optimization on a particular band, vary from very good to very bad. Some shortwavers even adjust the length of the cable to "improve" the SWR...

However, one should not forget about the essence, that no matching device, no matter how ingenious it may be, is not able to reduce the SWR in the antenna feeder. With it, you can achieve perfect matching only between our radio station and the matching device itself, located on the same desktop in the shack. The main effect achieved here is different - the transmitter, as they say, "managed to deceive", and the output stage will give out all possible power. But the power losses directly in the feeder itself have not disappeared anywhere.

As noted more than once, a conventional dipole with an SWR of about 1, designed for the 80m band, at a frequency of 7 MHz (where it is already a wave vibrator with an input resistance of about 4 kOhm) will have an SWR of about 53, and in the 20 m band we get SWR = 57. Let's assume that with the help of some matching device (tuner) we managed to get the SWR between the transceiver and the SU and on these ranges it is also equal to 1. But the feeder is still mismatched with the load (emitter). By using a two-wire line with relatively low losses, one could turn a blind eye to this, and still work on the air with varying success, but another problem immediately arises - how can one constructively bring that very open two-wire line to the operator's desk? After all, you won’t run out to the balcony every now and then to the matching device installed there! If it is possible to pass the conductors through the window - that's fine. And if not? And is it worth having a certain high-frequency radiation near your workplace? In addition, a matching device for a symmetrical feeder is incomparably more difficult to construct and set up than a matching device for an unbalanced load.

The proposed version of the antenna system based on the development of Oleg Safiullin, UA4PA, solves most of the questions raised. Such an antenna is by no means intended to replace other, much more efficient designs, but may be of interest to those radio amateurs who do not have sufficient resources, free space and suitable supports for hanging the antenna web.

Many shortwave beginners in the basic description of the UA4PA antenna are often scared off by the need to install a vertical pin 11.2 m high on the roof and the problem of placing counterweights of the same length in a limited space below it. Meanwhile, in the magazine "Radio", in former years almost the only source of information necessary for a radio amateur, the idea of ​​\u200b\u200busing this method matching to a dipole having almost any shoulder size. At the same time, it was noted that due to the increase in the effective radiating part, such an antenna works even better than a relatively short vertical in low-frequency ranges, and the dipole itself can also be successfully located in the form of an Inverted Vee. At my personal radio station (call sign in Soviet times - UB5LEW) for almost 20 years, a simple inclined beam 35.5 m long was successfully used as a reliable reserve, powered from the end, but connected to a matching device with the help of an appropriate piece of cable.

The very idea of ​​O. Safiullin was actively discussed in amateur radio circles and on the relevant forums on the Internet. The main disadvantage of such an antenna, its zealous opponents (however, mostly "theorists" who did not even set themselves the task of practical testing the design) called the operation of a coaxial cable in a standing wave mode - they say, everyone knows computer programs when analyzing losses, they simply “are horrified” 🙂

Yes, apparently, for QRO supporters, lovers of “pumping kilowatts”, this antenna is really not suitable - the cable can simply melt and burn out ... However, for many shortwavers who are content with the standard oscillatory power of an imported device of 100 W, losses in the cable that is functioning in the 100% standing wave mode (in this case, this is not a feeder at all, but a part of the antenna fabric itself, only almost not radiating!), are by no means as scary as they are painted!

Naturally, there are losses in any real feeder, but they can be reduced to some extent by using, for example, a cable with a higher impedance or better quality.

Previously, I used a 100-ohm cable PK-100-4-31 with a diameter of about 8 mm with a double braid and a copper-plated steel core, and now - PK-75-7-11. In order for it, rather thick and elastic, not to crawl around the desktop with a miniature and light box of a matching device, the short part of the line near the matching device - up to about half a meter long - is generally made of thin RG-58.

The indisputable advantage of the matching method proposed by Oleg Safiullin is the adjustment of the entire antenna system for operation on any range directly on the shortwave desktop. In this case, SWR = 1 is easily achieved between the transceiver and the matching device (and then the antenna itself begins!) the output stage will give out “on the mountain” all 100% of the prescribed power, and the only KPI allows, if necessary, to instantly adjust the antenna more precisely and at the edges of the ranges.

The disadvantages of such a matching device include only the need to select taps in the coil of the oscillatory circuit, as well as the limited use - only with one given antenna in its specific design and location. Any attempts to use a ready-made matching device with any other antenna will necessarily lead to a certain mismatch, and a complete reconfiguration of the entire device will inevitably be required.

Individual radio amateurs, having installed a vertical transmitter 11.2 m high and connected it through an arbitrary length of coaxial cable and a T-type matching device (for example, from MFJ), have achieved excellent results. Well, wonderful! But it should not be argued that in this case the “UA4PA antenna” is allegedly used, without noticing that nothing remains of the very idea of ​​​​matching “according to Safiullin”, except for the length of the pin ...

The control system diagram is shown below (for simplicity, taps are shown for only one range) and does not have any features - ordinary parallel oscillatory circuit(as in the original UA4PA antenna) with an indicator of the current flowing in the antenna.

Comparing the proposed matching device with the widely used T-shaped, L-shaped and U-shaped matchers, it is easy to notice the gain in ergonomics (one range switch and only one smooth adjustment knob) and in size. However, as they say, options are possible here, up to the use of roller variometers.

The antenna itself is a well-known G5RV design with a two-wire overhead line “dropped down” at one end.

The dimensions of the vibrator (material - bimetal copper/steel with a diameter of 2 mm) - with a total length of about 31 m - are selected based on the available placement possibilities on the ground. The upper part of the directly active canvas is a kind of vertical (unfortunately, to some extent, its upper end is close to the wall of a nine-story panel building - where can you go?), And the second half is, accordingly, a counterweight. The two-wire line leading to the balcony, and further, without any tricks, the cable itself (of course, taking into account the shortening factor) completes the length of the entire system to the required 42.5 m.

Line dimensions - the length of each conductor is 10.4 m, the material is copper wire with a diameter of 1.8 mm, insulating spacers installed every 30 cm are made of 3 mm thick fluoroplast sheet. The distance between the conductors is not critical, and for a wave resistance of 200 - 400 ohms it is in the range of 50 - 150 mm (in my antenna - 50 mm).
At the same time: a) there are no additional losses in the “balcony - center of the canvas” section due to the replacement of the coaxial cable with an overhead line, and b) there is a fairly comfortable continuation of the antenna-feeder device directly around the apartment (in my case, to the next room from the balcony) with a coaxial cable.

The only critical parameter is the required length of the cable segment from the two-wire line to the matching device, which is calculated by the formula:

Surplus in any convenient place can be rolled into the bay. O. Safiullin himself pointed out the desirability of using a cable with a higher wave impedance (to reduce losses), as well as the possibility of substituting into the formula instead of the value of 42.5 logically suggestive multiples of 85 or 21.3 m (in the latter case, the antenna will work only in the ranges from 40 to 10 m).

The design of the matching device

The dimensions of the matching device case I used are small - only 190x125x70mm, and it looks very harmoniously complete with the Yaesu FT-897 transceiver. To achieve the desired compactness of the device, I deliberately deviated from the classically accepted canons by reducing the distance between the coils and the walls of the case to the detriment of a certain degree of efficiency.

The design of the matching device:

Switch SA1 (according to the diagram above) - ordinary PGK, 11P4N (11 positions, 4 directions). KPI C1 - with a maximum capacitance of about 150 pF. You can use KPIs with a higher maximum capacitance, or even completely abandon additional capacitors and SA1.4 biscuits, but it should be borne in mind that the circuit setting will become much “sharper”.

By the way, even with a small excitation power, the voltage on the oscillatory circuit can reach a significant value. Additionally, “fastened” capacitors with an input power of about 100 W (imported transceiver or UW3DI with an output stage on a GU-29 lamp, etc.) must have an operating voltage of at least 2 kV (ordinary KSO-3 with a voltage of up to 500 V “flashes "). The remaining details are indicated on the schematic diagram or are visible in the photo of the matching device and do not require additional explanations.

Each radio amateur will freely select coils for the control system from any available with similar parameters - they are absolutely not critical, the total number of turns can be “estimated by eye”, based on the lowest frequency required range, and the taps will be selected during the tuning process. In the approach to the choice of winding products, one should be guided by one thing - it is desirable to achieve the highest possible quality factor of the coil. If possible, it is advisable to make coils from silver-plated wire (at least L1).

Inductor data: L1 is wound on a ceramic ribbed frame (or without it) with a diameter of 32 mm and contains 8 turns of silver-plated wire 02.2 mm, winding with a pitch of 5 mm; L2 is wound on a 060 mm ceramic frame and contains 23 turns of PEV-2 wire with a diameter of 1.2 mm, winding with a pitch of 1.8 mm.

The range-switched taps from the coils, counting from the upper (according to the diagram) output (their approximate position is indicated), as well as the capacitances of additional capacitors connected at low-frequency ranges, are shown in the table.

Setting
After sealing the connectors, armed with patience, tweezers and a soldering iron, you can start setting up the matching device. At the initial stage, with the help of elementary measuring instruments - GSS and a tube voltmeter, or GIR - it is advisable to select the circuit taps in ranges with the KPI rotor in the middle position and the transmitter disconnected from the matching device. Then, by controlling the SWR using the SWR meter connected between the transceiver and the matching device, or by looking at the LCD hidden in the "bourgeois" apparatus, the matching of the 50-ohm output of the transmitter with the circuit is selected, i.e. the tap is made at the point where the input impedance will be about 50 ohms. In this case, it should be taken into account that, most likely, it may be necessary to select the inclusion point in the antenna cable loop on each individual band.

Specifically, all the adjustment of the matching device is not difficult and is quite accessible even to a beginner shortwave (in this case, for simplicity and gaining initial experience, you can limit yourself to one range - 80 or 40m). And as a result, the radio amateur gets a simple, cheap, inconspicuous and hard-to-reach short-wave antenna for strangers, which allows you to work well on the air on all amateur KB bands even in cramped urban conditions!

By the way, in the range of 160m, I do not use the parallel circuit of the matching device, because the vibrator, with an available length of 42.5 m, is half-wave only for 3.5 MHz. Approximately equal in length to a quarter wave at 1.8 MHz, it is matched using a small additional coil connected in series (frame - 25 mm in diameter, PEV-2 wire - 1.5 mm in diameter, 18 turns, winding - turn to turn). For greater efficiency, you should also set the SU circuit itself to 160 m, while either including a special extension inductance between the circuit and the cable connector, or use the initial figure of 85 m in the formula for calculating the cable length. In this case, the method of setting the matching device to 1, 8 MHz will be similar to other bands.

results
In conclusion, a few words about the efficiency of the antenna. Due to the inclined arrangement of the vibrator, which to some extent approaches the vertical, a significant component of the radiation in the radiation pattern falls on the petal pressed to the ground, which is favorable for long-distance radio communications. When installing the antenna, any practically feasible variations are possible both with the spatial arrangement and length of the elements in any particular place, and with the dimensions of the matching line - the main thing is that the overall dimensions fit into the formula.

Fans of computer calculations can simulate the expected radiation patterns, as well as calculate the antenna efficiency and "unacceptable loss" in the cable 🙂

In the process of setting up the matching device on the FT-897 transceiver with an output power of 100 W in the 1.8 MHz band, radio communications were made with OH3XR, UA9KAA, LA3XI; in the range of 3.5 MHz - with UA0WB, RKOUT, E7 / DK9TN; in the 7 MHz band - with 4S7AB, P40L, VQ9JC; in the 10 MHz band - with 9M6XRO/P, TS7TI, OY6FRA; in the 14 MHz band - with KN6MV, 9Q500N, WH0DX (from the first call!), in the 18 MHz band - with KH0 / KT3Q, ZS6X, 9M2TO, in the 21 MHz band - with BD6JJX; BD1ISI, HS0ZEE; in the range of 24 MHz -CVQ9LA, 5Р5Х, EX8MLE; in the 28 MHz band - with 4J9M, OG20YL, IK2SND.

In fairness, I note that all radio communications are telegraphic, since of all other types of radiation I prefer this particular one.

The antenna in daily practical work on all amateur bands fully justified the expected performance and allows you to conduct confident radio communications with all continents and various expeditions, without experiencing any particular need for an additional power amplifier. However, by excluding a relatively low-current toggle switch from the circuit (here it is deliberately used, for the convenience of switching the antenna grounding) and increasing the electrical strength of the KPI and coils, it is quite possible to increase the oscillatory power of the transmitter to 300 - 500 watts. A similar design option was operated by the author for a long time together with various amplifiers on GU-50 lamps (from 2 to 4 pieces), while any noticeable, and even more so, significant heating of the cable, as well as television interference was not observed at all.

With appropriate settings, this matching device can be successfully used with another antenna (for example, Delta Loop) to increase the efficiency of its matching when working on all amateur bands.

I needed a transmit-receive antenna that would work on all HF and VHF bands and at the same time it did not need to be rebuilt and coordinated. The antenna should not have strict dimensions and should work in all conditions.

Recently, I have FT-857D at home, this (like many others) The transceiver does not have a tuner. They don’t let you on the roof, but you want to work on the air, so from the loggia, I lowered a piece of wire at an angle of 50 degrees, the length of which I didn’t even measure, but judging by the resonant frequency of 5.3 MHz, the length is about 14 meters. At first, I made different matching devices for this piece, everything worked and matched as usual, but it was inconvenient to run from the room to the loggia to tune the antenna to the desired range. Yes, and the noise level at 7.0, 3.6 and 1.9 MHz reached 7 points on the S-meter (high-rise building, near the main street and a bunch of wires). Then the idea came to make an antenna that would make less noise and it did not need to be rebuilt in ranges. Of course, this will slightly reduce efficiency.

Initially I liked the idea of ​​TTFD, but it is heavy, too noticeable, and a piece of wire was already hanging (don't take it off). In general, taking the principle of this antenna as a basis, I slightly changed its connection, and you can see what came of it in the picture. As a 50 ohm non-inductive resistor, an equivalent rated for 100 W of power is used. The counterweight is a piece of wire 5 meters long, which is laid along the perimeter of the loggia. I think that a few resonant balances will improve the performance of this antenna for transmission (however, like any other pin). Cable RK-50-11 goes to the radio station and has a length of about seven meters.

When this antenna is connected to a radio station, the air noise is reduced by 3 - 5 divisions on the S-meter, compared to the resonant one. Useful signals also fall slightly in level, but they are heard better. For transmission, the antenna has a SWR of 1:1 in the range of 1.5 - 450 MHz, so now I use it to work on all HF / VHF bands with a power of 100W. and everyone I hear answers me.

To make sure that the antenna works, I did some experiments. To begin with, I made two separate connections to the beam. The first is a shortening capacitance, which results in an elongated 7 MHz pin, which is perfectly matched and has an SWR = 1.0. The second is the broadband version described here with a resistor. Thus, I had the opportunity to quickly switch matching devices. Then I chose weak stations at 7 MHz, usually they were DL, IW, ON ... and listened to them, periodically changing matching devices. Reception was approximately the same on both antennas, but in the broadband version, the noise level was much lower, which subjectively improved the audibility of weak signals.

A comparison between an extended pole and a broadband antenna, for transmission in the 7MHz band, gave the following results:
.... connection with RW4CN: for extended GP 59+5, for broadband 58-59 (distance 1000km)
....communication with RA6FC: for extended GP 59+10, for broadband 59 (distance 3km)

As you might expect, a broadband antenna loses out to a resonant transmission. However, the loss is small, and with increasing frequency it will be even smaller, and in many cases it can be neglected. But the antenna really works in a continuous and very wide frequency range.

Due to the fact that the length of the radiating element is 14 meters, the antenna is really effective only up to 7 MHz, in the 3.6 MHz band many stations hear me poorly or do not answer at all, only local QSOs are possible on 1.9 MHz. At the same time, from 7 MHz and above, there are no problems with communication. Audibility is excellent, everyone responds, including DX, expeditions and all sorts of mobile radio stations. On VHF, I open all local repeaters and make FM QSOs, although on 430 MHz the horizontal polarization of the antenna is strongly affected.

This antenna can be used as the main, spare, receiving, emergency and anti-noise in order to better hear remote stations in the city. By placing it like a pin or by making a dipole, the results will be even better. You can ""turn"" into a broadband, any antenna already installed earlier (dipole or pin) and experiment with it, you only need to add a load resistor. Note that the length of the arm of the dipole or the length of the rod web does not matter, since the antenna has no resonances. The length of the canvas, in this case, only affects the efficiency. Attempts to calculate the characteristics of the antenna in MMANA failed. Apparently, the program cannot correctly calculate this type of antenna, this is indirectly confirmed by the TTFD calculation file, the results of which are very doubtful.

I haven't checked yet, but I'm guessing (similar to TTFD) that to increase the efficiency of the antenna, you need to add several resonant balances, increase the beam length to 20 - 40 meters or more (if you are interested in the 1.9 and 3.6 MHz bands).

Transformer option
Having worked on all HF-VHF bands on the option described above, I slightly redid the design by adding a 1: 9 transformer and a 450 ohm load resistor. Theoretically, the efficiency of the antenna should become greater. Changes in design and connection, you see in the picture. When measuring the uniformity of the overlap, with the MFJ device, a blockage was visible at frequencies from 15 MHz and higher (this is due to the unsuccessful brand of the ferrite ring), with a real antenna, this blockage remained, but the SWR was within the normal range. From 1.8 to 14 MHz SWR 1.0, from 14 to 28 MHz it gradually increased to 2.0. On the VHF bands, this option does not work, due to the high SWR.

Testing the antenna in real air gave the following results: The air noise during the transition from an extended GP to a broadband antenna decreased from 6-8 points to 5-7 points. When working on a transmission with a power of 60W, in the 7MHz band, the following reports were received:
RA3RJL, 59+ wideband, 59+ remote GP
UA3DCT, 56 wideband, 59 remote GP
RK4HQ, 55-57 wideband, 58-59 remote GP
RN4HDN, 55 wideband, 57 remote GP

On the F6BQU page, at the very bottom, a similar antenna with a terminating resistor is described. Article in French. So the goal is achieved, I made an antenna that works on all HF and VHF bands, which does not require coordination. Now you can work on the air and listen to it while lying on the couch, and switch bands only with the button on the radio station. Laziness rules the world. hee. Submit your feedback....

Option number three
I tried another option, broadband antenna matching. This is a classic 1:9 unbalanced transformer loaded with a 450 ohm resistor on one side and a 50 ohm cable on the other. The length of the beam does not really matter, but unlike the previous design, it is important that it does not fall into resonance on any amateur band. (for example 23 or 12 meters). then the SWR will be good everywhere. The transformer is wound on a ferrite ring, with three wires folded together, I got 5 turns, which must be evenly spaced around the circumference of the ring.
The load resistor can be made composite, for example, 15 pieces of 6k8 resistors of the MLT-2 type, will provide you with the opportunity to work in CW and SSB with a power of up to 100W. As grounding, you can use a beam of any length, water pipes, a stake driven into the ground, etc. The finished structure is placed in a box from which there is a PL connector for the cable and two terminals for the beam and ground. Operating frequency range 1.6 - 31 MHz.

Antennas shortwave
Practical designs for amateur radio antennas

The section presents a large number of different practical designs of antennas and other related devices. To facilitate the search, you can use the button "View a list of all published antennas". For more on the topic, see the CATEGORY subheading with regular additions to new publications.

Dipole with an off-centre feed point

Many shortwavers are interested in simple HF antennas that provide operation on several amateur bands without any switching. The most famous of these antennas is Windom with a single-wire feeder. But the price for the simplicity of manufacturing this antenna was and remains the inevitable interference with television and radio broadcasting when powered by a single-wire feeder and the accompanying showdown with neighbors.

The idea behind Windom dipoles seems to be simple. By shifting the feed point away from the center of the dipole, one can find such a ratio of arm lengths that the input impedances on several ranges become quite close. Most often, they look for dimensions at which it is close to 200 or 300 ohms, and matching with low-resistance supply cables is carried out using balancing transformers (BALUN) with a transformation ratio of 1:4 or 1:6 (for a cable with a characteristic impedance of 50 ohms). This is how, for example, the FD-3 and FD-4 antennas are made, which are produced, in particular, in series in Germany.

Radio amateurs construct similar antennas on their own. Certain difficulties, however, arise in the manufacture of balancing transformers, in particular, for operation in the entire short-wave range and when using power exceeding 100 W.

A more serious problem is that such transformers normally only work on a matched load. And this condition is obviously not met in this case - the input impedance of such antennas is really close to the required values ​​​​of 200 or 300, but obviously differs from them, and on all ranges. The consequence of this is that, to some extent, in such a design, the antenna effect of the feeder is preserved despite the use of a matching transformer and coaxial cable. And as a result, the use of balun transformers in these antennas, even of a rather complex design, does not always completely solve the TVI problem.

Alexander Shevelev (DL1BPD) managed, using matching devices on the lines, to develop a variant of matching Windom-dipoles that use power through a coaxial cable and do not have this drawback. They were described in the magazine “Radio Amateur. Vestnik SRR” (2005, March, pp. 21, 22).

As calculations show, the best result is obtained when using lines with wave impedances of 600 and 75 ohms. A 600 ohm line adjusts the input impedance of the antenna on all operating bands to a value of approximately 110 ohms, and a 75 ohm line transforms this resistance to a value close to 50 ohms.

Consider the implementation of such a Windom-dipole (ranges 40-20-10 meters). On fig. 1 shows the lengths of the arms and dipole lines on these ranges for a wire with a diameter of 1.6 mm. The total length of the antenna is 19.9 m. When using an insulated antenna cord, the lengths of the arms are made slightly shorter. A line with a characteristic impedance of 600 ohms and a length of approximately 1.15 meters is connected to it, and a coaxial cable with a characteristic impedance of 75 ohms is connected to the end of this line.

The latter, with a cable shortening factor equal to K = 0.66, has a length of 9.35 m. The reduced line length with a wave impedance of 600 Ohm corresponds to a shortening factor K = 0.95. With such dimensions, the antenna is optimized for operation in the frequency bands 7…7.3 MHz, 14…14.35 MHz and 28…29 MHz (with a minimum SWR at 28.5 MHz). The calculated SWR graph of this antenna for an installation height of 10 m is shown in fig. 2.

Using a cable with a wave impedance of 75 ohms in this case is actually not the best option. Lower SWR values ​​can be obtained using a cable with a characteristic impedance of 93 ohms or a line with a characteristic impedance of 100 ohms. It can be made from a coaxial cable with a characteristic impedance of 50 ohms (for example, http://dx.ardi.lv/Cables.html). If a line with a wave impedance of 100 ohms from a cable is used, it is advisable to include BALUN 1: 1 at its end.

To reduce the level of interference from a part of the cable with a wave impedance of 75 ohms, a choke should be made - a coil (bay) Ø 15-20 cm, containing 8-10 turns.

The radiation pattern of this antenna is practically the same as that of a similar Windom dipole with a balancing transformer. Its efficiency should be slightly higher than that of antennas using BALUN, and tuning should be no more difficult than tuning conventional Windom dipoles.

vertical dipole

It is well known that a vertical antenna has an advantage for working on long-distance paths, since its directivity pattern in the horizontal plane is circular, and the main lobe of the pattern in the vertical plane is pressed to the horizon and has a low radiation level at the zenith.

However, the manufacture of a vertical antenna is associated with the solution of a number of design problems. The use of aluminum pipes as a vibrator and the need for its effective operation to install a system of "radials" (counterweights) at the base of the "vertical", consisting of a large number of quarter-wave wires. If you use not a pipe as a vibrator, but a wire, the mast supporting it must be made of a dielectric and all the guys supporting the dielectric mast should also be dielectric, or broken into non-resonant segments by insulators. All this is associated with costs and is often impracticable constructively, for example, due to the lack of the necessary area to accommodate the antenna. Do not forget that the input impedance of the "verticals" is usually below 50 ohms, and this will also require its coordination with the feeder.

On the other hand, horizontal dipole antennas, which include antennas of the Inverted V type, are structurally very simple and cheap, which explains their popularity. The vibrators of such antennas can be made from almost any wire, and the masts for their installation can also be made from any material. The input impedance of horizontal dipoles or Inverted V is close to 50 ohms, and additional termination can often be dispensed with. The radiation patterns of the Inverted V antenna are shown in fig. one.

The disadvantages of horizontal dipoles include their non-circular radiation pattern in the horizontal plane and a large radiation angle in the vertical plane, which is acceptable mainly for operation on short paths.

An ordinary horizontal wire dipole is rotated vertically by 90 degrees. and we get a vertical full-size dipole. To reduce its length (in this case, the height), we use the well-known solution - "a dipole with bent ends". For example, a description of such an antenna is in the library files of I. Goncharenko (DL2KQ) for the MMANA-GAL program - AntShortCurvedCurved dipole.maa. By bending a part of the vibrators, we, of course, somewhat lose in antenna gain, but significantly gain in the required height of the mast. The bent ends of the vibrators should be located one above the other, while compensating for the radiation of vibrations with horizontal polarization, which is harmful in our case. A sketch of the proposed version of the antenna, called the Curved Vertical Dipole (CVD) by the authors, is shown in fig. 2.

Initial conditions: a dielectric mast 6 m high (fiberglass or dry wood), the ends of the vibrators are drawn with a dielectric cord (fishing line or kapron) at a slight angle to the horizon. The vibrator is made of copper wire with a diameter of 1...2 mm, bare or insulated. At the break points, the vibrator wire is attached to the mast.

If we compare the calculated parameters of the Inverted V and CVD antennas for the 14 MHz band, it is easy to see that due to the shortening of the radiating part of the dipole, the CVD antenna has 5 dB less gain, however, at a radiation angle of 24 degrees. (maximum CVD gain) the difference is only 1.6 dB. In addition, the Inverted V antenna has a horizontal ripple of up to 0.7 dB, i.e. in some directions it outperforms CVD in gain by only 1 dB. Since the calculated parameters of both antennas turned out to be close, only experimental verification of CVD and practical work on the air could help to make the final conclusion. Three CVD antennas were manufactured for the 14, 18 and 28 MHz bands according to the dimensions indicated in the table. All of them had the same design (see Fig. 2). The dimensions of the upper and lower arms of the dipole are the same. Our vibrators were made of a P-274 field telephone cable, and the insulators were made of Plexiglas. The antennas were mounted on a fiberglass mast 6 m high, while the top point of each antenna was at a height of 6 m above the ground. The bent parts of the vibrators were pulled off with a nylon cord at an angle of 20-30 degrees. to the horizon, since we did not have high objects for fastening guys. The authors made sure (this was also confirmed by modeling) that the deviation of the bent sections of the vibrators from the horizontal position by 20-30 degrees. practically does not affect the characteristics of CVD.

Modeling in MMANA software shows that such a curved vertical dipole is easily matched to a 50 ohm coaxial cable. It has a small radiation angle in the vertical plane and a circular radiation pattern in the horizontal (Fig. 3).

The design simplicity made it possible to change one antenna to another within five minutes, even in the dark. The same coaxial cable was used to power all variants of the CVD antenna. He approached the vibrator at an angle of about 45 degrees. To suppress common-mode current, a tubular ferrite magnetic core (filter latch) is installed on the cable near the connection point. It is desirable to install several similar magnetic circuits on a cable section 2 ... 3 m long in the vicinity of the antenna web.

Since the antennas were made of vole, its insulation increased the electrical length by about 1%. Therefore, antennas made according to the dimensions given in the table needed some shortening. The adjustment was made by adjusting the length of the lower bent section of the vibrator, which is easily accessible from the ground. By folding part of the length of the lower bent wire into two, you can fine-tune the resonant frequency by moving the end of the bent section along the wire (a kind of tuning loop).

The resonant frequency of the antennas was measured with an MF-269 antenna analyzer. All antennas had a clearly defined minimum SWR within amateur bands not exceeding 1.5. For example, for a 14 MHz antenna, the minimum SWR at 14155 kHz was 1.1, and the bandwidth was 310 kHz for SWR 1.5 and 800 kHz for SWR 2.

For comparative tests, an Inverted V of the 14 MHz band was used, mounted on a metal mast 6 m high. The ends of the vibrators were at a height of 2.5 m above the ground.

To obtain objective estimates of the signal level under QSB conditions, the antennas were repeatedly switched from one to another with a switching time of no more than one second.

Table

Radio communications were carried out in SSB mode with a transmitter power of 100 W on routes ranging from 80 to 4600 km long. On the 14 MHz band, for example, all correspondents who were at a distance of more than 1000 km noted that the signal level with the CVD antenna was one or two points higher than with the Inverted V. At a distance of less than 1000 km, the Inverted V had some minimal advantage .

These tests were carried out during a period of relatively poor radio wave conditions on the HF bands, which explains the lack of longer distance communications.

During the absence of ionospheric transmission in the 28 MHz band, we made several surface wave radio contacts with Moscow shortwaves from our QTH with this antenna over a distance of about 80 km. On a horizontal dipole, even raised a little higher than the CVD antenna, it was impossible to hear any of them.

The antenna is made of cheap materials and does not require much space for placement.

When using a nylon fishing line as guy lines, it may well be disguised as a flagpole (a cable broken into sections of 1.5 ... (Fig. 4).

Files in .maa format for self-study of the properties of the described antennas are located.

Vladislav Shcherbakov (RU3ARJ), Sergey Filippov (RW3ACQ),

Moscow city

A modification of the well-known T2FD antenna is proposed, which allows you to cover the entire range of HF amateur radio frequencies, losing quite a bit to a half-wave dipole in the 160-meter range (0.5 dB on short-range and about 1.0 dB on DX routes).
With exact repetition, the antenna starts working immediately and does not need tuning. A feature of the antenna is noticed: static interference is not perceived, and in comparison with the classical half-wave dipole. In this performance, the reception of the ether is quite comfortable. Very weak DX stations are normally heard, especially on low-frequency bands.

Long-term operation of the antenna (more than 8 years) allowed us to deservedly classify it as a low-noise receiving antenna. Otherwise, in terms of efficiency, this antenna is practically not inferior to a band half-wave dipole or Inverted Vee on any of the ranges from 3.5 to 28 MHz.

And one more observation (based on the feedback from distant correspondents) - during the communication there are no deep QSBs. Of the 23 modifications made to this antenna, the one proposed here deserves special attention and can be recommended for mass repetition. All proposed dimensions of the antenna-feeder system are calculated and accurately verified in practice.

Antenna fabric

The dimensions of the vibrator are shown in the figure. The halves (both) of the vibrator are symmetrical, the excess length of the “inner corner” is cut off on the spot, and a small platform (mandatory insulated) is attached there to connect to the supply line. Ballast resistor 240 Ohm, film (green), rated for 10 watts. You can also use any other resistor of the same power, the main thing is that the resistance must be non-inductive. Copper wire - insulated, with a cross section of 2.5 mm. Spacers - wooden slats in a section with a section of 1 x 1 cm with a varnish coating. The distance between the holes is 87 cm. We use a nylon cord for stretch marks.

Overhead power line

For the power line, we use copper wire PV-1, with a section of 1 mm, vinyl spacers. The distance between the conductors is 7.5 cm. The length of the entire line is 11 meters.

Author's installation option

A metal, grounded from below, mast is used. The mast is installed on a 5-storey building. Mast - 8 meters from a pipe Ø 50 mm. The ends of the antenna are placed 2 m from the roof. The core of the matching transformer (SHPTR) is made from a line transformer TVS-90LTs5. The coils are removed there, the core itself is glued with Supermoment glue to a monolithic state and with three layers of varnished fabric.

Winding is made in 2 wires without twisting. The transformer contains 16 turns of single-core insulated copper wire Ø 1 mm. The transformer has a square (sometimes rectangular) shape, so 4 pairs of turns are wound on each of the 4 sides - the best current distribution option.

SWR in the entire range is obtained from 1.1 to 1.4. The SPTR is placed in a well-soldered tin screen with a braided feeder. From the inside, the middle terminal of the transformer winding is securely soldered to it.

After assembly and installation, the antenna will work immediately and in almost any conditions, that is, located low above the ground or above the roof of a house. She has a very low level of TVI (television interference), and this may additionally be of interest to radio amateurs working from villages or summer residents.

50 MHz Loop Feed Array Yagi Antenna

Yagi antennas (Yagi) with a frame vibrator located in the plane of the antenna are called LFA Yagi (Loop Feed Array Yagi) and are characterized by a larger operating frequency range than conventional Yagi. One popular LFA Yagi is Justin Johnson's (G3KSC) 5-element design on 6m.

The antenna scheme, the distances between the elements and the dimensions of the elements are shown in the table and in the drawing below.

Dimensions of the elements, distances to the reflector and diameters of aluminum tubes, from which the elements are made according to the table: The elements are installed on a traverse about 4.3 m long from a square aluminum profile with a cross section of 90 × 30 mm through insulating adapter strips. The vibrator is powered by a 50-ohm coaxial cable through a balun transformer 1:1.

The antenna is tuned for the minimum SWR in the middle of the range by selecting the position of the end U-shaped parts of the vibrator from tubes with a diameter of 10 mm. It is necessary to change the position of these inserts symmetrically, i.e., if the right insert is extended by 1 cm, then the left one must be extended by the same amount.

SWR meter on strip lines

SWR meters widely known from amateur radio literature are made using directional couplers and are a single-layer coil or ferrite ring core with several turns of wire. These devices have a number of disadvantages, the main of which is that when measuring high powers, a high-frequency “pickup” appears in the measuring circuit, which requires additional costs and efforts to shield the detector part of the SWR meter to reduce the measurement error, and with the formal attitude of a radio amateur to manufacturing instrument, the SWR meter can cause the impedance of the feed line to change with frequency. The proposed SWR meter based on strip directional couplers is devoid of such shortcomings, is structurally designed as a separate independent device and allows you to determine the ratio of direct and reflected waves in the antenna circuit with an input power of up to 200 W in a frequency range of 1 ... 50 MHz with a wave impedance of the feeder line 50 ohm. If you only need to have an indicator of the output power of the transmitter or control the antenna current, you can use this device: When measuring SWR in lines with a characteristic impedance other than 50 ohms, the values ​​​​of resistors R1 and R2 should be changed to the value of the characteristic impedance of the measured line.

The construction of the SWR meter

The SWR meter is made on a board made of double-sided foil-coated PTFE 2 mm thick. As a replacement, it is possible to use double-sided fiberglass.

Line L2 is made on the back side of the board and is shown as a broken line. Its dimensions are 11×70 mm. Pistons are inserted into the holes of the L2 line under the connectors XS1 and XS2, which are flared and soldered together with L2. The common bus on both sides of the board has the same configuration and is shaded on the board diagram. Holes were drilled in the corners of the board, into which pieces of wire 2 mm in diameter were inserted, soldered on both sides of the common bus. Lines L1 and L3 are located on the front side of the board and have dimensions: a straight section 2×20 mm, the distance between them is 4 mm and are located symmetrically to the longitudinal axis of the line L2. The offset between them along the longitudinal axis L2 is -10 mm. All radio elements are located on the side of the strip lines L1 and L2 and are soldered with an overlap directly to the printed conductors of the SWR meter board. The printed circuit board conductors should be silver-plated. The assembled board is soldered directly to the contacts of connectors XS1 and XS2. The use of additional connecting conductors or coaxial cable is unacceptable. The finished SWR meter is placed in a box made of non-magnetic material with a thickness of 3 ... 4 mm. The common bus of the SWR meter board, the instrument case and connectors are electrically interconnected. The SWR is counted as follows: in the S1 “Direct” position, using R3, set the microammeter needle to the maximum value (100 μA) and by transferring S1 to “Reverse”, the SWR value is counted. In this case, the instrument reading of 0 μA corresponds to SWR 1; 10 µA - SWR 1.22; 20 μA - SWR 1.5; 30 µA - SWR 1.85; 40 μA - SWR 2.33; 50 μA - SWR 3; 60 μA - SWR 4; 70 µA - SWR 5.67; 80 µA - 9; 90 µA - SWR 19.

Nine band HF antenna

The antenna is a variation of the well-known multi-band WINDOM antenna, in which the feed point is offset from the center. In this case, the input impedance of the antenna in several amateur KB bands is approximately 300 ohms,
which allows using both a single wire and a two-wire line with the corresponding characteristic impedance as a feeder, and, finally, a coaxial cable connected through a matching transformer. In order for the antenna to work in all nine amateur HF bands (1.8; 3.5; 7; 10; 14; 18; 21; 24 and 28 MHz), essentially two WINDOM antennas are connected in parallel (see above Fig. a): one with a total length of about 78 m (l/2 for the 1.8 MHz band) and the other with a total length of about 14 m (l/2 for the 10 MHz band and l for the 21 MHz band). Both radiators are powered by a single coaxial cable with a wave impedance of 50 ohms. The matching transformer has a resistance transformation ratio of 1:6.

The approximate location of the antenna emitters in the plan is shown in Fig. b.

When the antenna was installed at a height of 8 m above a well-conducting "ground", the standing wave ratio in the 1.8 MHz band did not exceed 1.3, in the 3.5, 14. 21, 24 and 28 MHz bands - 1.5, in the 7. 10 and 18 bands MHz - 1.2. In the ranges of 1.8, 3.5 MHz, and to some extent in the range of 7 MHz with a suspension height of 8 m, the dipole, as is known, radiates mainly at large angles to the horizon. Therefore, in this case, the antenna will be effective only for short-range communications (up to 1500 km).

The connection diagram of the windings of the matching transformer to obtain a transformation ratio of 1: 6 is shown in fig.c.

Windings I and II have the same number of turns (as in a conventional transformer with a transformation ratio of 1:4). If the total number of turns of these windings (and it depends primarily on the dimensions of the magnetic circuit and its initial magnetic permeability) is n1, then the number of turns n2 from the connection point of windings I and II to the tap is calculated by the formula n2=0.82n1.t

Horizontal frames are very popular. Rick Rogers (KI8GX) has experimented with a "tilted frame" attached to a single mast.

To install the “tilted frame” option with a perimeter of 41.5 m, a mast 10 ... 12 meters high and an auxiliary support about two meters high are required. These masts are attached to the opposite corners of the frame, which has the shape of a square. The distance between the masts is chosen so that the angle of inclination of the frame relative to the ground is within 30 ... 45 °. The feed point of the frame is located in the upper corner of the square. The frame is powered by a coaxial cable with a wave impedance of 50 ohms. According to KI8GX measurements in this variant, the frame had SWR = 1.2 (minimum) at a frequency of 7200 kHz, SWR = 1.5 (rather “dumb” minimum) at frequencies above 14100 kHz, SWR = 2.3 in the entire 21 MHz band, SWR = 1.5 (minimum) at a frequency of 28400 kHz. At the edges of the ranges, the SWR value did not exceed 2.5. According to the author, a slight increase in the frame length will shift the minima closer to the telegraph sections and will make it possible to obtain an SWR of less than 2 within all operating bands (except 21 MHz).

QST #4 2002

Vertical antenna for 10, 15 meters

A simple combined vertical antenna for 10 and 15 m bands can be made both for work in stationary conditions and for out-of-town trips. The antenna is a vertical radiator (Fig. 1) with a trap filter (trap) and two resonant counterweights. The trap is tuned to the selected frequency in the range of 10 m, therefore, in this range, the emitter is the L1 element (see figure). In the range of 15 m, the ladder inductor is an extension and, together with the L2 element (see figure), brings the total length of the emitter to 1/4 of the wavelength on the range of 15 m. The emitter elements can be made from pipes (in a stationary antenna) or from wire (for a hiking antenna) mounted on fiberglass pipes. A "trap" antenna is less "capricious" in setting up and operating than an antenna consisting of two radiators located side by side. The dimensions of the antenna are shown in Fig. 2. The emitter consists of several sections of duralumin pipes of different diameters, connected to one another through adapter bushings. The antenna is powered by a 50-ohm coaxial cable. To prevent the flow of high-frequency current along the outer side of the cable sheath, power is supplied through a current balun (Fig. 3), made on an FT140-77 ring core. The winding consists of four turns of RG174 coaxial cable. The electrical strength of this cable is quite sufficient to work with a transmitter with an output power of up to 150 watts. When working with a more powerful transmitter, either a cable with a Teflon dielectric (for example, RG188) should be used, or a cable with a large diameter, which, of course, will require a ferrite ring of the appropriate size to wind. The balun is installed in a suitable dielectric box:

It is recommended that a non-inductive two-watt resistor with a resistance of 33 kOhm should be installed between the vertical radiator and the support pipe on which the antenna is mounted, which will prevent the accumulation of static charge on the antenna. The resistor is conveniently placed in the box in which the balun is installed. The design of the ladder can be any.
So, an inductor can be wound on a piece of PVC pipe with a diameter of 25 mm and a wall thickness of 2.3 mm (the lower and upper parts of the emitter are inserted into this pipe). The coil contains 7 turns of copper wire with a diameter of 1.5 mm in varnish insulation, wound in increments of 1-2 mm. The required coil inductance is 1.16 µH. A high-voltage (6 kV) ceramic capacitor with a capacity of 27 pF is connected in parallel to the coil, and the result is a parallel oscillatory circuit at a frequency of 28.4 MHz.

Fine tuning of the resonant frequency of the circuit is carried out by compressing or stretching the turns of the coil. After tuning, the turns are fixed with glue, but it should be borne in mind that an excessive amount of glue applied to the coil can significantly change its inductance and lead to an increase in dielectric losses and, accordingly, a decrease in antenna efficiency. In addition, the trap can be made of coaxial cable by winding 5 turns on a 20 mm PVC pipe, but it is necessary to provide for the possibility of changing the winding pitch to ensure fine tuning to the desired resonant frequency. The design of the ladder for its calculation is very convenient to use the Coax Trap program, which can be downloaded from the Internet.

Practice shows that such ladders work reliably with 100-watt transceivers. To protect the ladder from environmental influences, it is placed in a plastic pipe, which is closed from above with a plug. Counterweights can be made from bare wire with a diameter of 1 mm, and it is desirable to space them as far apart as possible. If a wire in plastic insulation is used for counterweights, then they should be shortened somewhat. So, counterweights made of copper wire with a diameter of 1.2 mm in vinyl insulation with a thickness of 0.5 mm should have a length of 2.5 and 3.43 m for the ranges of 10 and 15 m, respectively.

Antenna tuning begins in the 10 m range, after making sure that the trap is tuned to the selected resonant frequency (for example, 28.4 MHz). The minimum SWR in the feeder is achieved by changing the length of the lower (up to the ladder) part of the emitter. If this procedure is unsuccessful, then it will be necessary to change the angle at which the counterweight is located relative to the emitter, the length of the counterweight and, possibly, its location in space, to a small extent. Only after that they are taken for tuning the antenna in the range of 15 m. ) parts of the radiator achieve a minimum SWR. If it is impossible to achieve an acceptable SWR, then the solutions recommended for tuning the 10 m antenna should be applied. In the prototype antenna in the frequency band 28.0-29.0 and 21.0-21.45 MHz, the SWR did not exceed 1.5.

Tuning Antennas and Loops with a Jammer

To work with this noise generator circuit, you can use any type of relay with the appropriate supply voltage and with a normally closed contact. In this case, the higher the relay supply voltage, the higher the level of interference generated by the generator. To reduce the level of interference on the devices under test, it is necessary to carefully shield the generator, and supply power from a battery or accumulator to prevent interference from entering the network. In addition to the adjustment of noise-protected devices, with such an interference generator, it is possible to measure and adjust high-frequency equipment and its components.

Determination of the resonant frequency of the circuits and the resonant frequency of the antenna

When using a continuous range survey receiver or wavemeter, the resonant frequency of the circuit under test can be determined from the maximum noise level at the output of the receiver or wavemeter. To eliminate the influence of the generator and receiver on the parameters of the measured circuit, their coupling coils should have the minimum possible connection with the circuit. When connecting the jammer to the WA1 antenna under test, it is possible to determine its resonant frequency or frequencies in the same way as measuring the circuit.

I. Grigorov, RK3ZK

Broadband aperiodic antenna T2FD

The construction of antennas at low frequencies due to large linear dimensions causes quite certain difficulties for radio amateurs due to the lack of space necessary for these purposes, the complexity of manufacturing and installing high masts. Therefore, when working on surrogate antennas, many use interesting low-frequency bands mainly for local communications with a hundred watts per kilometer amplifier.

In amateur radio literature, there are descriptions of fairly efficient vertical antennas, which, according to the authors, "practically do not occupy an area." But it is worth remembering that a significant amount of space is required to accommodate a system of counterweights (without which a vertical antenna is ineffective). Therefore, in terms of footprint, it is more advantageous to use linear antennas, especially those made according to the popular "inverted V" type, since only one mast is required for their construction. However, the transformation of such an antenna into a dual-band antenna greatly increases the occupied area, since it is desirable to place radiators of different ranges in different planes.

Attempts to use switchable extension elements, tuned power lines and other ways to turn a piece of wire into an all-band antenna (with available suspension heights of 12-20 meters) most often lead to the creation of “supersurrogates” by tuning which you can conduct amazing tests of your nervous system.

The proposed antenna is not "super efficient", but allows normal operation in two or three bands without any switching, is characterized by relative stability of parameters and does not need painstaking tuning. Having a high input impedance at low suspension heights, it provides better efficiency than simple wire antennas. This is a slightly modified well-known T2FD antenna, popular in the late 60s, unfortunately, almost not used at present. Obviously, she fell into the category of "forgotten" because of the absorbing resistor, which dissipates up to 35% of the transmitter power. It is precisely because they are afraid of losing these percentages that many consider the T2FD to be a frivolous design, although they calmly use a pin with three counterweights on the HF bands, efficiency. which does not always reach 30%. I had to hear a lot of "against" in relation to the proposed antenna, often unfounded. I will try to briefly state the pros, thanks to which T2FD was chosen to work on the low bands.

In an aperiodic antenna, which in its simplest form is a conductor with wave impedance Z, loaded on an absorbing resistance Rh=Z, the incident wave, having reached the load Rh, is not reflected, but completely absorbed. Due to this, the traveling wave mode is established, which is characterized by constancy maximum value current Imax along the entire conductor. On fig. 1(A) shows the current distribution along the half-wave vibrator, and fig. 1(B) - along the traveling wave antenna (losses due to radiation and in the antenna conductor are conditionally not taken into account. The shaded area is called the current area and is used to compare simple wire antennas.

In the theory of antennas, there is the concept of the effective (electrical) length of the antenna, which is determined by replacing the real vibrator with an imaginary one, along which the current is distributed evenly, having the same value of Imax,
the same as the test vibrator (i.e. the same as in Fig. 1(B)). The length of the imaginary vibrator is chosen such that the geometric area of ​​the current of the real vibrator is equal to the geometric area of ​​the imaginary one. For a half-wave vibrator, the length of the imaginary vibrator, at which the current areas are equal, is equal to L / 3.14 [pi], where L is the wavelength in meters. It is not difficult to calculate that the length of a half-wave dipole with geometric dimensions = 42 m (range 3.5 MHz) is electrically equal to 26 meters, which is the effective length of the dipole. Returning to fig. 1(B), it is easy to see that the effective length of an aperiodic antenna is almost equal to its geometric length.

The experiments carried out in the 3.5 MHz band allow us to recommend this antenna to radio amateurs as a good cost-benefit option. An important advantage of T2FD is its broadband and performance at suspension heights that are “ridiculous” for low-frequency ranges, starting from 12-15 meters. For example, an 80-meter dipole with such a suspension height turns into a “military” anti-aircraft antenna,
because radiates up about 80% of the input power. The main dimensions and design of the antenna are shown in Fig. 2, Fig. 3 shows the upper part of the mast, where a matching-balancing transformer T and absorbing resistance R are installed. The design of the transformer in Fig. 4

You can make a transformer on almost any magnetic circuit with a permeability of 600-2000 NN. For example, a core from TVS of lamp TVs or a pair of rings folded together with a diameter of 32-36 mm. It contains three windings wound in two wires, for example, MGTF-0.75 sq. mm (used by the author). The cross section depends on the power supplied to the antenna. The wires of the windings are laid tightly, without pitch and twists. In the place indicated in Fig. 4, the wires should be crossed.

It is enough to wind 6-12 turns in each winding. If you carefully consider Fig. 4, then the manufacture of the transformer does not cause any difficulties. The core should be protected from corrosion with varnish, preferably oil or moisture resistant glue. The absorbing resistance should theoretically dissipate 35% of the input power. It has been experimentally established that the MLT-2 resistors, in the absence of direct current at frequencies of the KB ranges, withstand 5-6-fold overloads. With a power of 200 W, 15-18 MLT-2 resistors connected in parallel are sufficient. The resulting resistance should be in the range of 360-390 ohms. With the dimensions indicated in Fig. 2, the antenna operates in the ranges of 3.5-14 MHz.

For operation in the 1.8 MHz band, it is desirable to increase the total length of the antenna to at least 35 meters, ideally 50-56 meters. With the correct implementation of the transformer T, the antenna does not need any tuning, you just need to make sure that the SWR is in the range of 1.2-1.5. Otherwise, the error should be sought in the transformer. It should be noted that with a popular 4:1 transformer based on a long line (one winding to two wires), the antenna performance deteriorates sharply, and the SWR can be 1.2-1.3.

German Quad Antenna for 80, 40, 20, 15, 10 and even 2m

Most urban radio amateurs face the problem of placing a shortwave antenna due to limited space.

But if there is a place for hanging a wire antenna, then the author suggests using it and making "GERMAN Quad /images/book/antenna". He reports that it works well on 6 amateur bands 80, 40, 20, 15, 10 and even 2 meters. The antenna circuit is shown in the figure. For its manufacture, exactly 83 meters of copper wire with a diameter of 2.5 mm will be required. The antenna is a square with a side of 20.7 meters, which is suspended horizontally at a height of 30 feet - that's about 9 meters. The connecting line is made of 75 ohm coaxial cable. According to the author, the antenna has a gain of 6 dB with respect to the dipole. At 80 meters it has fairly high radiation angles and works well at distances of 700 ... 800 km. Starting from the 40 meter range, the radiation angles in the vertical plane decrease. On the horizon, the antenna does not have any directivity priorities. Its author also proposes to use it for mobile-stationary work in the field.

3/4 Long Wire Antenna

Most of its dipole antennas are based on 3/4L wavelength on each side. One of them - "Inverted Vee" we will consider.
The physical length of the antenna is greater than its resonant frequency, increasing the length to 3/4L expands the antenna's bandwidth compared to a standard dipole and lowers the vertical radiation angles, making the antenna more long-range. In the case of a horizontal arrangement in the form of an angular antenna (half-rhombus), it acquires very decent directional properties. All of these properties also apply to the antenna, made in the form of "INV Vee". The input impedance of the antenna is reduced and special measures are required to match the power line. With a horizontal suspension and a total length of 3/2L, the antenna has four main and two minor lobes. The author of the antenna (W3FQJ) gives a lot of calculations and diagrams for different dipole arm lengths and suspension catches. According to him, he derived two formulas containing two "magic" numbers to determine the length of the arm of the dipole (in feet) and the length of the feeder in relation to the amateur bands:

L (each half) = 738 / F (in MHz) (in feet feet),
L (feeder) = 650/F (in MHz) (in feet).

For frequency 14.2MHz,
L (each half) = 738 / 14.2 = 52 feet (feet),
L (feeder) = 650/F = 45 feet 9 inches.
(Convert to the metric system yourself, the author of the antenna considers everything in feet). 1 ft =30.48 cm

Then for a frequency of 14.2 MHz: L (each half) \u003d (738 / 14.2) * 0.3048 \u003d 15.84 meters, L (feeder) \u003d (650 / F14.2) * 0.3048 \u003d 13.92 meters

P.S. For other selected ratios of arm lengths, the coefficients change.

In the 1985 Radio Yearbook, an antenna was published with a slightly strange name. It is depicted as an ordinary isosceles triangle with a perimeter of 41.4 m and, obviously, therefore, did not attract attention. As it turned out later, very in vain. I just needed a simple multi-band antenna, and I hung it at a low height - about 7 meters. The length of the supply cable RK-75 is about 56 m (half-wave repeater).

The measured SWR values ​​practically coincided with those given in the Yearbook. Coil L1 is wound on an insulating frame with a diameter of 45 mm and contains 6 turns of PEV-2 wire with a thickness of 2 ... 2 mm. HF transformer T1 is wound with MGShV wire on a ferrite ring 400NN 60x30x15 mm, contains two windings of 12 turns. The size of the ferrite ring is not critical and is selected based on the input power. The power cable is connected only as shown in the figure, if it is turned on the other way around, the antenna will not work. The antenna does not require tuning, the main thing is to accurately maintain its geometric dimensions. When operating on the 80 m range, compared to other simple antennas, it loses on transmission - the length is too small. At the reception, the difference is almost not felt. Measurements carried out by G. Bragin's HF bridge ("R-D" No. 11) showed that we are dealing with a non-resonant antenna.

The frequency response meter shows only the resonance of the power cable. It can be assumed that a fairly universal antenna (from simple ones) has turned out, it has small geometric dimensions and its SWR is practically independent of the height of the suspension. Then it became possible to increase the height of the suspension to 13 meters above the ground. And in this case, the SWR value on all main amateur bands, except for the 80-meter one, did not exceed 1.4. At eighties, its value ranged from 3 to 3.5 at the upper frequency of the range, so the simplest antenna tuner. Later it was possible to measure the SWR on the WARC bands. There, the SWR value did not exceed 1.3. The drawing of the antenna is shown in the figure.

GROUND PLANE at 7 MHz

When working on low-frequency bands, a vertical antenna has a number of advantages. However, due to its large size, it is not possible to install it everywhere. Reducing the height of the antenna leads to a drop in radiation resistance and an increase in losses. A wire mesh screen and eight radial wires are used as an artificial "ground". The antenna is powered by a 50-ohm coaxial cable. SWR of an antenna tuned with series capacitor, was equal to 1.4. Compared to the previously used antenna of the "Inverted V" type, this antenna provided a loudness gain of 1 to 3 points when working with DX.

QST, 1969, N 1 Radio amateur S. Gardner (K6DY / W0ZWK) applied a capacitive load at the end of the Ground Plane type antenna on the 7 MHz band (see figure), which made it possible to reduce its height to 8 m. The load is a cylinder of wire mesh.

P.S. In addition to QST, a description of this antenna was published in the Radio magazine. In the year 1980, while still a novice radio amateur, he made this version of the GP. capacitive load and artificial earth made from galvanized mesh, since in those days there was plenty of this. Indeed, the antenna outperformed Inv.V. on long runs. But after placing the classic 10-meter GP, I realized that it was not worth bothering with making a container at the top of the pipe, but it would be better to make it two meters longer. The complexity of manufacturing does not pay off the design, not to mention the materials for the manufacture of the antenna.

Antenna DJ4GA

In appearance, it resembles the generatrix of a disc-cone antenna, and its overall dimensions do not exceed the overall dimensions of a conventional half-wave dipole. Comparison of this antenna with a half-wave dipole having the same suspension height showed that it is somewhat inferior to a dipole with short-range SHORT-SKIP communications, but is much more efficient it for long-distance communications and for communications carried out with the help of the earth wave. The described antenna has a large bandwidth compared to a dipole (by about 20%), which in the 40 m range reaches 550 kHz (in SWR level up to 2). With a corresponding change in size, the antenna can be used on other ranges. The introduction of four rejector circuits into the antenna, similarly to how it was done in the W3DZZ type antenna, makes it possible to implement an efficient multi-band antenna. The antenna is powered by a coaxial cable with a wave impedance of 50 ohms.

P.S. I made this antenna. All dimensions were maintained, identical to the drawing. It was installed on the roof of a five-story building. When switching from a triangle of the 80-meter range, located horizontally, on the near tracks, the loss was 2-3 points. It was checked during communications with stations of the Far East (Equipment for receiving R-250). Won the triangle maximum one and a half points. When compared with the classic GP, lost one and a half points. The equipment used was self-made, UW3DI amplifier 2xGU50.

All-wave amateur antenna

The French amateur radio antenna is described in the CQ magazine. According to the author of this design, the antenna gives a good result when working on all shortwave amateur bands - 10, 15, 20, 40 and 80 m. It does not require any special careful calculation (except for calculating the length of the dipoles) or fine tuning.

It should be set immediately so that the maximum of the directivity characteristic is oriented in the direction of preferential connections. The feeder of such an antenna can be either two-wire, with a wave impedance of 72 ohms, or coaxial, with the same wave impedance.

For each band, except for the 40 m band, there is a separate half-wave dipole in the antenna. On the 40-meter band, the 15 m band dipole works well in such an antenna. All dipoles are tuned to the middle frequencies of the corresponding amateur bands and are connected in the center of it in parallel to two short copper wires. The feeder is soldered to the same wires from below.

Three plates of dielectric material are used to isolate the center wires from each other. At the ends of the plates, holes are made for attaching the wires of the dipoles. All wire connections in the antenna are soldered, and the feeder connection point is wrapped with plastic tape to prevent moisture from entering the cable. The calculation of the length L (m) of each dipole is carried out according to the formula L=152/fcp, where fav is the middle frequency of the range in MHz. Dipoles are made of copper or bimetallic wire, guys are made of wire or cord. Antenna height - any, but not less than 8.5 m.

P.S. It was also installed on the roof of a five-story building, a dipole of 80 meters was excluded (the size and configuration of the roof did not allow). The masts were made of dry pine, butt 10 cm in diameter, height 10 meters. The antenna sheets were made from a welding cable. The cable was cut, one core consisting of seven copper wires was taken. In addition, I twisted it a little to increase the density. Showed itself as normal, separately suspended dipoles. It's a perfectly acceptable option for work.

Actively powered switchable dipoles

The switchable antenna is a type of two-element active-powered linear antennas and is designed to operate in the 7 MHz band. The gain is about 6 dB, the front-to-back ratio is 18 dB, the side-to-side ratio is 22-25 dB. DN width at half power level about 60 degrees For 20 m range L1=L2= 20.57 m: L3 = 8.56 m
Bimetal or ant. cord 1.6 ... 3 mm.
I1 =I2= 14m cable 75 ohm
I3= 5.64m cable 75 ohm
I4 =7.08m 50 ohm cable
I5 = free length cable 75 ohm
K1.1 - RF relay REV-15

As can be seen from Fig. 1, two active vibrators L1 and L2 are located at a distance L3 (phase shift 72 degrees) from each other. The elements are powered in antiphase, the total phase shift is 252 degrees. K1 provides switching of the direction of radiation by 180 degrees. I3 - phase-shifting loop I4 - quarter-wave matching segment. Antenna tuning consists in adjusting the dimensions of each element in turn according to the minimum SWR with the second element short-circuited through a half-wave repeater 1-1 (1.2). SWR in the middle of the range does not exceed 1.2, at the edges of the range -1.4. The dimensions of the vibrators are given for a suspension height of 20 m. From a practical point of view, especially when working in competitions, a system consisting of two similar antennas located perpendicular to each other and separated in space has proven itself well. In this case, a switch is placed on the roof, instantaneous switching of DN in one of four directions is achieved. One of the options for the location of antennas among typical urban developments is proposed in Fig. 2. This antenna has been used since 1981, it has been repeatedly repeated at different QTHs, with its help tens of thousands of QSOs have been made with more than 300 countries of the world.

From the UX2LL website, the original source “Radio No. 5 p. 25 S. Firsov. UA3LD

40m beam antenna with switchable beam pattern

The antenna, schematically shown in the figure, is made of copper wire or bimetal with a diameter of 3 ... 5 mm. The matching line is made of the same material. Relays from the RSB radio station were used as switching relays. The matcher uses a variable capacitor from a conventional broadcast receiver, carefully protected from moisture. The relay control wires are attached to a nylon stretch cord running along the center line of the antenna. The antenna has a wide radiation pattern (about 60°). The ratio of radiation forward-backward is within 23 ... 25 dB. Estimated gain - 8 dB. The antenna was operated for a long time at the UK5QBE station.

Vladimir Latyshenko (RB5QW) Zaporozhye

P.S. Out of my roof, as a field option, out of interest, I experimented with an antenna made as Inv.V. The rest I scooped up and performed as in this design. The relay used automotive, four-pin, metal case. Since I used a 6ST132 battery for power. Equipment TS-450S. One hundred watts. Really result, as they say on the face! When switching to the east, Japanese stations began to be called. VK and ZL, in the direction were somewhat to the south, made their way with difficulty through the stations of Japan. About the West I will not describe, everything thundered! Antenna is great! Too bad there isn't room on the roof!

Multiband dipole on WARC bands

The antenna is made of copper wire with a diameter of 2 mm. The insulating spacers are made of textolite 4 mm thick (it can be made of wooden planks) on which insulators for external wiring are fixed with bolts (Mb). The antenna is powered by a coaxial cable of the PK 75 type of any reasonable length. The lower ends of the insulator strips must be stretched with a nylon cord, then the entire antenna stretches well and the dipoles do not overlap with each other. A number of interesting DX-QSOs were made on this antenna with all continents using the UA1FA transceiver with one GU29 without RA.

Antenna DX 2000

Shortwaves often use vertical antennas. To install such antennas, as a rule, a small free space is required, therefore, for some radio amateurs, especially those living in densely populated urban areas), a vertical antenna is the only way to go on the air on short waves. One of the still little-known vertical antennas operating on all HF bands is DX 2000 antenna. Under favorable conditions, the antenna can be used for DX radio communications, but when working with local correspondents (at distances up to 300 km.), It is inferior to a dipole. As you know, a vertical antenna mounted above a well-conducting surface has almost ideal "DX-properties", i.e. very low beam angle. It does not require a tall mast. Multi-band vertical antennas are usually constructed with trap filters and they work in much the same way as single-band quarter-wave antennas. Broadband vertical antennas used in professional HF radio communication have not found a great response in HF amateur radio, but they have interesting properties.

On the The figure shows the most popular vertical antennas among radio amateurs - a quarter-wave radiator, an electrically extended vertical radiator and a vertical radiator with ladders. An example of the so-called. exponential antenna is shown on the right. Such a bulk antenna has good efficiency in the frequency band from 3.5 to 10 MHz and quite satisfactory matching (SWR<3) вплоть до верхней границы КВ диапазона (30 МГц). Очевидно, что КСВ = 2 - 3 для транзисторного передатчика очень нежелателен, но, учитывая широкое распространение в настоящее время антенных тюнеров (часто автоматических и встроенных в трансивер), с высоким КСВ в фидере антенны можно мириться. Для лампового усилителя, имеющего в выходном каскаде П - контур, как правило, КСВ = 2 - 3 не представляет проблемы. Вертикальная антенна DX 2000 является своеобразным гибридом узкополосной четвертьволновой антенны (Ground plane), настроенной в резонанс в некоторых любительских диапазонах, и широкополосной экспоненциальной антенны. Основа антенны-трубчатый излучатель длиной около 6 м. Он собран из алюминиевых труб диаметром 35 и 20 мм., вставленных друг в друга и образующих четвертьволновый излучатель на частоту примерно 7 МГц. Настройку антенны на частоту 3,6 МГц обеспечивает включённая последовательно катушка индуктивности 75 МкГн, к которой подсоединена тонкая алюминиевая a tube 1.9 m long. The matching device uses a 10 μH inductor, to the taps of which a cable is connected. in addition, 4 side radiators made of copper wire in PVC insulation with a length of 2480, 3500, 5000 and 5390 mm are connected to the coil. For fastening, the emitters are extended with nylon cords, the ends of which converge under the 75 μH coil. When operating in the 80 m range, grounding or counterweights are required, at least for lightning protection. To do this, you can dig several galvanized strips deep into the ground. When mounting the antenna on the roof of the house, it is very difficult to find any "ground" for HF. Even a well-made roof ground does not have a zero potential with respect to the "ground", so it is better to use metal ones for a grounding device on a concrete roof.
structures with large surface area. In the matching device used, ground is connected to the output of the coil, in which the inductance before the tap, where the cable braid is connected, is 2.2 μH. Such a small inductance is not sufficient to suppress the currents flowing along the outer side of the coaxial cable braid, therefore, a shut-off choke should be made by winding about 5 m of cable into a coil with a diameter of 30 cm. For effective operation of any quarter-wave vertical antenna (including the DX 2000), it is imperative to make a system of quarter-wave counterweights. The DX 2000 antenna was made at the SP3PML radio station (Military club of shortwave and radio amateurs PZK).

A sketch of the antenna design is shown in the figure. The emitter was made of durable dural tubes with a diameter of 30 and 20 mm. Stretch marks used to fasten copper wires-emitters must be resistant to both stretching and weather conditions. The diameter of copper wires should be chosen no larger than 3 mm (to limit the dead weight), and it is desirable to use wires in insulation, which will ensure resistance to weather conditions. To fix the antenna, use strong insulating guy wires that do not stretch when weather conditions change. The spacers for the copper wires of the radiators should be made of a dielectric (for example, PVC pipes with a diameter of 28 mm), but for increased rigidity they can be made of a wooden block or other, as light as possible, material. The entire antenna structure is mounted on a steel pipe no longer than 1.5 m, previously rigidly attached to the base (roof), for example, with steel braces. The antenna cable can be connected via a connector, which must be electrically isolated from the rest of the structure.

Coils with an inductance of 75 μH (node ​​A) and 10 μH (node ​​B) are designed to tune the antenna and match its impedance with the characteristic impedance of the coaxial cable. The antenna is tuned to the required sections of the HF ranges by selecting the inductance of the coils and the position of the taps. The antenna installation site should be free from other structures, best of all, at a distance of 10-12 m, then the influence of these structures on the electrical characteristics of the antenna is small.

Addendum to the article:

If the antenna is installed on the roof of an apartment building, its installation height must be more than two meters from the roof to the counterweights (for safety reasons). I categorically do not recommend connecting the antenna ground to the common ground of a residential building or to any fittings that make up the roof structure (in order to avoid huge mutual interference). Grounding is better to use individual, located in the basement of the house. It should be stretched in the communication niches of the building or in a separate pipe pinned to the wall from top to bottom. It is possible to use a lightning arrester.

V. Bazhenov UA4CGR

Method for Accurate Calculation of Cable Length

Many radio amateurs use 1/4 wave and 1/2 wave coaxial lines. They are needed as resistance transformers for impedance followers, phase delay lines for active powered antennas, etc. The simplest method, but also the most inaccurate, is the method of multiplying a fraction of a wavelength by coefficient 0.66, but it is not always suitable when it is necessary to accurately enough
calculate the length of the cable, for example 152.2 degrees.

Such accuracy is necessary for antennas with active power, where the quality of the antenna depends on the phasing accuracy.

Coefficient 0.66 is taken as an average, because for the same dielectric, the dielectric constant can deviate noticeably, and therefore the coefficient will also deviate. 0.66. I would like to propose the method described by ON4UN.

It is simple, but requires instruments (a transceiver or generator with a digital scale, a good SWR meter and a dummy load of 50 or 75 ohms, depending on the Z. cable) fig.1. From the figure you can understand how this method works.

The cable from which it is planned to make the desired segment must be shorted at the end.

Next, we turn to a simple formula. Let's say we need a segment of 73 degrees to operate at a frequency of 7.05 MHz. Then our cable segment will be exactly 90 degrees at a frequency of 7.05 x (90/73) = 8.691 MHz. at this frequency, the cable length will be 90 degrees, and for a frequency of 7.05 MHz it will be exactly 73 degrees. When shorted, it will invert the short circuit into infinite resistance and thus have no effect on the SWR meter reading at 8.691 MHz. For these measurements, either a sufficiently sensitive SWR meter is required, or a sufficiently powerful load dummy, because. you will have to increase the power of the transceiver for confident operation of the SWR meter if it does not have enough power for normal operation. This method gives very high measurement accuracy, which is limited by the accuracy of the SWR meter and the accuracy of the transceiver scale. For measurements, you can also use the VA1 antenna analyzer, which I mentioned earlier. An open cable will indicate zero impedance at the calculated frequency. It is very convenient and fast. I think this method will be very useful for radio amateurs.

Alexander Barsky (VAZTTT), vаЗ [email protected] com

Asymmetrical GP Antenna

The antenna is (Fig. 1) nothing more than a "groundplane" with an elongated vertical radiator 6.7 m high and four counterweights 3.4 m long each. A broadband impedance transformer (4:1) is installed at the feed point.

At first glance, the indicated dimensions of the antenna may seem incorrect. However, adding the length of the radiator (6.7 m) and the counterweight (3.4 m), we see that the total length of the antenna is 10.1 m. Taking into account the velocity factor, this is Lambda / 2 for the 14 MHz band and 1 Lambda for 28 MHz.

The resistance transformer (Fig. 2) is made according to the generally accepted method on a ferrite ring from the OS of a black-and-white TV and contains 2 × 7 turns. It is installed at a point where the input impedance of the antenna is about 300 ohms (a similar excitation principle is used in modern modifications of the Windom antenna).

The average vertical diameter is 35 mm. To achieve resonance at the desired frequency and more accurate matching with the feeder, it is possible to change the size and position of the counterweights within a small range. In the author's version, the antenna has a resonance at frequencies of about 14.1 and 28.4 MHz (SWR = 1.1 and 1.3, respectively). If desired, by approximately doubling the dimensions indicated in Fig. 1, it is possible to achieve antenna operation in the 7 MHz band. Unfortunately, in this case, the radiation angle in the 28 MHz band will “spoil”. However, using a U-shaped matching device installed near the transceiver, you can use the author's version of the antenna to operate in the 7 MHz band (though with a loss of 1.5 ... 2 points with respect to the half-wave dipole), as well as in the ranges 18, 21 , 24 and 27 MHz. For five years of operation, the antenna showed good results, especially in the 10-meter range.

Shortwavers often have difficulty installing full-size antennas for operation on the low-frequency KB bands. One of the possible versions of a shortened (about two times) dipole of the 160 m range is shown in the figure. The total length of each of the emitter halves is about 60 m.

They are folded in three, as shown schematically in Figure (a) and held in this position by two end (c) and several intermediate (b) insulators. These insulators, as well as a similar central insulator, are made of a non-hygroscopic dielectric material with a thickness of approximately 5 mm. The distance between adjacent conductors of the antenna web is 250 mm.

A coaxial cable with a characteristic impedance of 50 ohms is used as a feeder. The antenna is tuned to the average frequency of the amateur band (or its required section - for example, telegraph) by moving two jumpers connecting its extreme conductors (in the figure they are shown by dashed lines), and observing the symmetry of the dipole. Jumpers must not have electrical contact with the center conductor of the antenna. With the dimensions indicated in the figure, the resonant frequency of 1835 kHz was achieved by installing jumpers at a distance of 1.8 m from the ends of the web. The standing wave coefficient at the resonant frequency was 1.1. Data on its dependence on frequency (i.e., on the bandwidth of the antenna) are not available in the article.

Antenna for 28 and 144 MHz

Rotating directional antennas are required for sufficiently effective operation in the 28 and 144 MHz bands. However, it is usually not possible to use two separate antennas of this type in a radio station. Therefore, the author made an attempt to combine the antennas of both ranges, making them in the form of a single design.

The dual-band antenna is a double “square” at 28 MHz, on the carrier traverse of which a nine-element wave channel at 144 MHz is fixed (Fig. 1 and 2). As practice has shown, their mutual influence on each other is insignificant. The influence of the wave channel is compensated by some reduction in the perimeters of the "square" frames. “Square”, in my opinion, improves the parameters of the wave channel, increasing the gain and suppression of reverse radiation. The antennas are fed using feeders from a 75-ohm coaxial cable. The “square” feeder is included in the gap in the lower corner of the vibrator frame (on the left in Fig. 1). A slight asymmetry with this inclusion causes only a slight distortion of the radiation pattern in the horizontal plane and does not affect the other parameters.

The wave channel feeder is connected through a balancing U-elbow (Fig. 3). As shown by the SWR measurements in the feeders of both antennas does not exceed 1.1. The antenna mast can be made of a steel or duralumin pipe with a diameter of 35-50 mm. A gearbox is attached to the mast, combined with a reversible engine. A “square” traverse made of pine wood is screwed to the gearbox flange with the help of two metal plates with M5 bolts. Traverse cross section - 40X40 mm. At its ends, crosses are reinforced, which are supported by eight wooden “square” poles with a diameter of 15-20 mm. The frames are made of bare copper wire with a diameter of 2 mm (you can use wire PEV-2 1.5 - 2 mm). The perimeter of the reflector frame is 1120 cm, the vibrator is 1056 cm. The wave channel can be made of copper or brass tubes or rods. Its traverse is fixed on the “square” traverse with two brackets. Antenna settings have no features.

With an exact repetition of the recommended sizes, it may not be needed. Antennas have shown good results over several years of work at the RA3XAQ radio station. A lot of DX contacts were made on 144 MHz - with Bryansk, Moscow, Ryazan, Smolensk, Lipetsk, Vladimir. More than 3.5 thousand QSOs were installed on 28 MHz, among them - with VP8, CX, LU, VK, KW6, ZD9, etc. The design of the dual-band antenna was repeated three times by Kaluga radio amateurs (RA3XAC, RA3XAS, RA3XCA) and also received positive ratings .

P.S. In the eighties of the last century, there was exactly such an antenna. Mostly made to work through low-orbit satellites ... RS-10, RS-13, RS-15. I used UW3DI with Zhutyaevsky transverter, and to receive R-250. Everything worked out well with ten watts. The squares on the ten worked well, a lot of VK, ZL, JA, etc. ... Yes, and the passage was wonderful then!

Extended version W3DZZ

The antenna shown in the figure is an extended version of the well-known W3DZZ antenna, adapted to operate on the bands 160, 80, 40 and 10 m. To suspend its canvas, a “span” of about 67 m is required.

The power cable can have a characteristic impedance of 50 or 75 ohms. The coils are wound on nylon frames (water pipes) with a diameter of 25 mm with PEV-2 wire 1.0 turn to turn (38 in total). Capacitors C1 and C2 are made up of four series-connected capacitors KSO-G with a capacity of 470 pF (5%) for an operating voltage of 500V. Each chain of capacitors is placed inside the coil and filled with sealant.

For fastening capacitors, you can also use a fiberglass plate with foil patches, to which the leads are soldered. The circuits are connected to the antenna web as shown in the figure. When using the above elements, there were no failures during the operation of the antenna in conjunction with a radio station of the first category. The antenna, suspended between two nine-story buildings and fed through a RK-75-4-11 cable about 45 m long, provided an SWR of no more than 1.5 at frequencies of 1840 and 3580 kHz and no more than 2 in the range of 7 ... 7.1 and 28, 2…28.7 MHz. The resonant frequency of the notch filters L1C1 and L2C2, measured by the GIR before connecting to the antenna, was 3580 kHz.

W3DZZ with coaxial cable traps

This design is based on the ideology of the W3DZZ antenna, but the barrier circuit (trap) at 7 MHz is made of coaxial cable. The drawing of the antenna is shown in Fig. 1, and the design of the coaxial ladder is shown in Fig. 2. The vertical end parts of the 40-meter dipole sheet have a size of 5 ... 10 cm and are used to tune the antenna to the required part of the range. The ladders are made of a 50 or 75-ohm cable 1.8 m long, laid in a twisted coil with a diameter of 10 cm , as shown in fig. 2. The antenna is powered by a coaxial cable through a balancing device of six ferrite rings, dressed on the cable near the power points.

P.S. In the manufacture of the antenna as such, no tuning was required. Particular attention was paid to sealing the ends of the ladders. First, I filled the ends with electrical wax, you can use paraffin from an ordinary candle, then covered it with silicone sealant. Which is sold in auto shops. The best quality sealant is grey.

Antenna "Fuchs" for a range of 40 m

Luc Pistorius (F6BQU)
Translation by Nikolai Bolshakov (RA3TOX), E-mail: boni(doggie)atnn.ru

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The variant of the matching device shown in Fig. 1 differs in that the fine tuning of the length of the antenna web is carried out from the “nearby” end (next to the matching device). This is really very convenient, since it is impossible to pre-set the exact length of the antenna web. The environment will do its job and eventually change the resonant frequency of the antenna system. In this design, tuning the antenna to resonance is carried out with a piece of wire about 1 meter long. This piece is close to you and is handy for resonating the antenna. In the author's version, the antenna is installed on the garden plot. One end of the wire goes to the attic, the other is fixed on a pole 8 meters high, installed in the depths of the garden. The length of the antenna wire is 19 m. In the attic, the end of the antenna is connected by a length of 2 meters to a matching device. In total, the total length of the antenna web is -21 m. The counterweight, 1 m long, is located together with the SU in the attic of the house. Thus, the whole structure is under the roof and, therefore, protected from atmospheric elements.

For the 7 MHz range, the device elements have the following ratings:
Cv1 = Cv2 = 150pF;
L1 - 18 turns of copper wire with a diameter of 1.5 mm on a frame with a diameter of 30 mm (PVC pipe);
L1 - 25 turns of copper wire with a diameter of 1 mm on a frame with a diameter of 40 mm (PVC pipe); We tune the antenna to a minimum SWR. First, with the capacitor Cv1 we set the minimum SWR, then we try to reduce the SWR with the capacitor Cv2 and finally make the adjustment, choosing the length of the compensating segment (counterweight). Initially, we select the length of the antenna wire a little more than half a wave and then compensate it with a counterweight. The Fuchs antenna is a familiar stranger. An article under this title talked about this antenna and two options for matching devices for it, proposed by the French radio amateur Luc Pistorius (F6BQU).

VP2E Field Antenna

The VP2E (Vertically Polarized 2-Element) antenna is a combination of two half-wave radiators, due to which it has a two-way symmetrical radiation pattern with soft minima. The antenna has a vertical (see name) polarization of radiation and a radiation pattern pressed to the ground in the vertical plane. The antenna provides a gain of +3 dB compared to an omnidirectional radiator in the direction of radiation maxima and suppression of the order of -14 dB in the dips of the radiation pattern.

The single-band version of the antenna is shown in Fig. 1, its dimensions are summarized in the table.
Element Length in L Length for the 80-m range I1 = I2 0.492 39 m I3 0.139 11 m h1 0.18 15 m h2 0.03 2.3 m The radiation pattern is shown in Fig. 2. For comparison, the radiation patterns of a vertical radiator and a half-wave dipole are superimposed on it. Figure 3 shows a five-band version of the VP2E antenna. Its resistance at the feed point is about 360 ohms. When the antenna was powered by a cable with a resistance of 75 ohms through a 4:1 matching transformer on a ferrite core, the SWR was 1.2 on the range of 80 m; 40 m - 1.1; 20 m - 1.0; 15 m - 2.5; 10 m - 1.5. Probably, when powered by a two-wire line through an antenna tuner, better matching can be achieved.

"Secret" antenna

In this case, the vertical "legs" have a length of 1/4, and the horizontal part - 1/2. Two vertical quarter-wave emitters are obtained, powered in antiphase.

An important advantage of this antenna is that the radiation resistance is about 50 ohms.

It is energized at the bend point, with the central core of the cable connected to the horizontal part, and the braid to the vertical part. Before making an antenna for the 80m range, I decided to mock up at a frequency of 24.9 MHz, because I had an inclined dipole for this frequency, and therefore, there was something to compare with. At first I listened to the NCDXF beacons and did not notice the difference: somewhere better, somewhere worse. When UA9OC, located 5 km away, gave a weak tuning signal, all doubts disappeared: in the direction perpendicular to the canvas, the U-shaped antenna has an advantage of at least 4 dB with respect to the dipole. Then there was an antenna for 40 m and, finally, for 80 m. Despite the simplicity of the design (see Fig. 1), it was not easy to hook it on the tops of poplars in the yard.

I had to make a halberd with a string of steel millimeter wire and an arrow from a 6 mm duralumin tube 70 cm long with a weight in the bow and with a rubber tip (just in case!). At the rear end of the arrow, I fixed a 0.3 mm fishing line with a cork, and with it I launched the arrow to the top of the tree. With the help of a thin fishing line, I tightened another, 1.2 mm, with which I suspended the antenna from a 1.5 mm wire.

One end turned out to be too low, the kids would certainly have pulled it (the yard is a common one!), So I had to bend it and put the tail horizontally at a height of 3 m from the ground. For power, I used a 50-ohm cable with a diameter of 3 mm (in terms of insulation) for ease and as less noticeable. The tuning consists in adjusting the length, because the surrounding objects and the ground lower the calculated frequency somewhat. It must be remembered that we shorten the end closest to the feeder by D L \u003d (D F / 300,000) / 4 m, and the far end is three times longer.

It is assumed that the diagram in the vertical plane is flattened from above, which manifests itself in the effect of "leveling" the signal strength from far and near stations. In the horizontal plane, the diagram is elongated in the direction perpendicular to the antenna web. It is difficult to find trees 21 meters high (for an 80 m range), so you have to bend the lower ends and let them go horizontally, while the antenna resistance decreases. Apparently, such an antenna is inferior to a full-sized GP, since the radiation pattern is not circular, but it does not need counterweights! Quite pleased with the results. At least this antenna seemed to me much better than the Inverted-V that preceded it. Well, for the “Field Day” and for the not very “cool” DXpedition on low-frequency bands, it is probably not equal to it.

From the UX2LL website

Compact 80m loop antenna

Many radio amateurs have suburban dachas and often the small size of the site on which the house is located does not allow them to have a sufficiently effective HF antenna.

For DX it is preferable that the antenna radiates at low angles to the horizon. In addition, its designs should be easily repeatable.

The proposed antenna (Fig. 1) has a radiation pattern similar to that of a vertical quarter-wave radiator. The maximum of its radiation in the vertical plane is at an angle of 25 degrees to the horizon. Also, one of the advantages of this antenna is the simplicity of design, since for its installation it is enough to use a twelve-meter metal mast. The antenna canvas can be made of a P-274 field telephone wire. Power is supplied to the middle of any of the vertically located sides. Subject to the specified dimensions, its input impedance is in the range of 40 ... 55 Ohm.

Practical tests of the antenna showed that it gives a gain in signal level for remote correspondents on routes of 3000 ... .6000 km in comparison with such antennas as “half-wave Inverted Vee? horizontal Delta-Loop" and a quarter-wave GP with two radials. The difference in signal level when compared with the "half-wave dipole" antenna on routes over 3000 km reaches 1 point (6 dB). The measured SWR was 1.3-1.5 over the range.

RV0APS Dmitry SHABANOV Krasnoyarsk

Receiving antenna for 1.8 - 30 MHz

Many people take various radios with them when they go out into the countryside. Which are now available enough. Various brands of Grundig satellit, Degen, Tecsun ... As a rule, a piece of wire is used for the antenna, in principle, which is quite enough. The antenna shown in the figure is a variation of the ABV antenna, and has a radiation pattern. When receiving on the Degen DE1103 radio receiver, it showed its selective qualities, the signal to the correspondent increased by 1-2 points when it was directed.

Short dipole 160 meters

An ordinary dipole is perhaps one of the simplest but most effective antennas. However, for a range of 160 meters, the length of the radiating part of the dipole exceeds 80 m, which usually causes difficulties in its installation. One of the possible ways to overcome them is to introduce shortening coils into the emitter. Shortening the antenna will usually reduce its efficiency, but sometimes the radio amateur is forced to make such a compromise. A possible version of the dipole with extension coils for a range of 160 meters is shown in fig. 8. The total dimensions of the antenna do not exceed the dimensions of a conventional dipole for a range of 80 meters. Moreover, it is easy to turn such an antenna into a dual-band one by adding relays that would close both coils. In this case, the antenna turns into a regular dipole for a range of 80 meters. If there is no need to work on two bands, and the place to install the antenna makes it possible to use a dipole with a length greater than 42 m, then it is advisable to use an antenna with the maximum possible length.

The inductance of the extension coil in this case is calculated by the formula: Here L is the inductance of the coil, μHp; l - length of half of the radiating part, m; d is the diameter of the antenna wire, m; f - operating frequency, MHz. According to the same formula, the inductance of the coil is also calculated if the place for installing the antenna is less than 42 m. However, it should be borne in mind that with a significant shortening of the antenna, its input resistance noticeably decreases, which creates difficulties in matching the antenna with the feeder, and this, in particular, further worsens its effectiveness.

DL1BU antenna modification

During the year, my radio station of the second category has been operating a simple antenna (see Fig. 1), which is a modification of the DL1BU antenna. It operates on 40, 20 and 10 m, does not require the use of a symmetrical feeder, is well matched, and easy to manufacture. A transformer on a ferrite ring is used as a matching and balancing element. brand VCh-50 with a section of 2.0 sq.cm. The number of turns of its primary winding is 15, the secondary is 30, the wire is PEV-2. 1 mm in diameter. When using a ring of a different section, it is necessary to re-select the number of turns using the diagram shown in Fig. 2. As a result of the selection, it is necessary to obtain a minimum SWR in the range of 10 meters. The antenna made by the author has an SWR of 1.1 at 40 m, 1.3 at 20 m and 1.8 at 10 m.

V. KONONOV (UY5VI) Donetsk

P.S. In the manufacture of the structure, I used a U-shaped core from a horizontal transformer of the TV, without changing the turns, I received a similar SWR value, with the exception of the 10 meter range. The best SWR was 2.0, and naturally changed with frequency.

Shortened antenna for 160 meters

The antenna is an asymmetric dipole, which is powered through a matching transformer with a coaxial cable with a wave impedance of 75 ohms. The antenna is best made of bimetal with a diameter of 2 ... 3 mm - the antenna cord and copper wire are pulled out over time, and the antenna is upset.

The matching transformer T can be made on a ring magnetic circuit with a cross section of 0.5 ... 1 cm2 made of ferrite with an initial magnetic permeability of 100 ... 600 (better - grade NN). It is possible, in principle, to use the magnetic circuits from the fuel assemblies of old TVs, which are made of HH600 material. The transformer (it must have a transformation ratio of 1: 4) is wound into two wires, and the windings A and B (the indices "n" and "k" indicate the beginning and end of the winding, respectively) are connected, as shown in Fig. 1b.

For the windings of the transformer, it is best to use a stranded installation wire, but you can also use the usual PEV-2. Winding is carried out with two wires at once, laying them tightly, coil to coil, along the inner surface of the magnetic circuit. Overlapping of wires is not allowed. On the outer surface of the ring, the turns are placed with a uniform pitch. The exact number of double turns is not significant - it can be in the range of 8 ... 15. The manufactured transformer is placed in a plastic cup of the appropriate size (Fig. 1c pos. 1) and filled with epoxy resin. In the uncured resin in the center of the transformer 2, screw 5 with a length of 5 ... 6 mm is sunk head down. It is used to fasten a transformer and a coaxial cable (using clip 4) to a textolite plate 3. This plate, 80 mm long, 50 mm wide and 5 ... 8 mm thick, forms the central antenna insulator - antenna sheets are also attached to it. The antenna is tuned to a frequency of 3550 kHz by selecting the length of each antenna sheet according to the minimum SWR (in Fig. 1 they are indicated with some margin). It is necessary to shorten the shoulders gradually by about 10-15 cm at a time. After completing the settings, all connections are carefully soldered, and then filled with paraffin. Be sure to cover the bare part of the braid of the coaxial cable with paraffin. As practice has shown, paraffin better than other sealants protects antenna parts from moisture. Paraffin coating does not age in air. The antenna made by the author had a bandwidth at SWR = 1.5 on the 160 m band - 25 kHz, on the 80 m band - about 50 kHz, on the 40 m band - about 100 kHz, on the 20 m band - about 200 kHz. On the 15 m band, the SWR was in the range of 2 ... 3.5, and on the 10 m band - in the range of 1.5 ... 2.8.

Laboratory of the CRC DOSAAF. 1974

Automotive HF Antenna DL1FDN

In the summer of 2002, despite poor communication conditions on the 80m band, I made a QSO with Dietmar, DL1FDN/m, and was pleasantly surprised by the fact that my correspondent was working from a moving car. Intrigued, I inquired about the output power of his transmitter and the design of the antenna . Dietmar. DL1FDN / m, willingly shared information about his homemade car antenna and kindly allowed me to talk about it. The information in this note was recorded during our QSO. Obviously, his antenna really works! Dietmar uses an antenna system, the design of which is shown in the figure. The system includes an emitter, an extension coil and a matching device (antenna tuner). The emitter is made of a copper-plated steel pipe 2 m long, mounted on an insulator. The extension coil L1 is wound turn to turn. . For operation in the range of 40 m, the L1 coil contains 18 turns wound with 02 mm wire on a 0100 mm frame. In the ranges of 20, 17, 15, 12 and 10 m, part of the turns of the coil of the range of 40 m is used. Taps on these ranges are selected experimentally. The matching device is an LC circuit consisting of a variable inductor L2, which has a maximum inductance of 27 μH (it is advisable not to use a ball variometer). Variable capacitor C1 must have a maximum capacitance of 1500 ... 2000 pF. With a transmitter power of 200 W (this is the power used by DL1FDN / m), the gap between the plates of this capacitor must be at least 1 mm. Capacitors C2, SZ - K15U, but at the specified power you can use KSO-14 or similar.

S1 - ceramic switch. The antenna is tuned to a specific frequency according to the minimum SWR meter reading. The cable connecting the matching device to the SWR meter and transceiver has a characteristic impedance of 50 ohms, and the SWR meter is calibrated to a 50 ohm dummy antenna.

If the output impedance of the transmitter is 75 ohms, a 75 ohm coaxial cable should be used, and the SWR meter should be "balanced" on a dummy 75 ohm antenna. Using the described antenna system and operating from a moving vehicle, DL1FDN made many interesting QSOs on the 80m band, including QSOs with other continents.

I. Podgorny (EW1MM)

Compact HF Antenna

Small-sized loop antennas (the perimeter of the loop is much smaller than the wavelength) are used in the KB bands mainly as receiving ones. Meanwhile, with an appropriate design, they can be successfully used at amateur radio stations and as transmitters. Such an antenna has a number of important advantages: Firstly, its quality factor is at least 200, which can significantly reduce interference from stations operating at neighboring frequencies. The small bandwidth of the antenna, of course, makes it necessary to adjust it even within the same amateur band. Secondly, a small-sized antenna can operate in a wide frequency range (frequency overlap reaches 10!). And finally, it has two deep minima at small radiation angles (the figure-of-eight radiation pattern). This allows you to rotate the frame (which is easy to do with its small dimensions) to effectively suppress interference from specific directions. The antenna is a frame (one turn), which is tuned to the operating frequency by a variable capacitor - KPI. The shape of the coil is not fundamental and can be any, but for design reasons, as a rule, frames in the form of a square are used. The operating frequency range of the antenna depends on the size of the loop. The minimum operating wavelength is approximately 4L (L is the perimeter of the loop). Frequency overlap is determined by the ratio of the maximum and minimum capacitance values ​​of KPI. When using conventional capacitors, the frequency overlap of the loop antenna is approximately 4, with vacuum capacitors - up to 10. With a transmitter output power of 100 W, the currents in the loop reach tens of amperes, therefore, to obtain acceptable values ​​​​of the efficiency, the antenna must be made of copper or brass pipes sufficiently large diameter (approximately 25 mm). The connections on the screws must ensure reliable electrical contact, excluding the possibility of its deterioration due to the appearance of a film of oxides or rust. It is best to solder all connections. A variant of a compact loop antenna designed to operate in the 3.5-14 MHz amateur bands.

A schematic drawing of the entire antenna is shown in Figure 1. In fig. 2 shows the design of the communication loop with the antenna. The frame itself is made of four copper pipes 1000 long and 25 mm in diameter. A CPE is included in the lower corner of the frame - it is placed in a box that excludes the effects of atmospheric moisture and precipitation. This KPI with a transmitter output power of 100 W should be designed for an operating voltage of 3 kV. The antenna is fed with a coaxial cable with a wave impedance of 50 Ohms, at the end of which a communication loop is made. The upper section of the loop in Figure 2 with the braid removed to a length of about 25 mm must be protected from moisture, i.e. some kind of compound. The loop is securely attached to the frame in its upper corner. The antenna is mounted on a mast with a height of about 2000 mm made of insulating material. The antenna specimen made by the author had an operating frequency range of 3.4 ... 15.2 MHz. The standing wave ratio was 2 in the 3.5 MHz band and 1.5 in the 7 and 14 MHz bands. Comparing it with full-size dipoles, installed at the same height, showed that in the 14 MHz band both antennas are equivalent, at 7 MHz the signal level of the loop antenna is 3 dB lower, and at 3.5 MHz - by 9 dB. These results were obtained for large radiation angles. For such radiation angles, when communicating over a distance of up to 1600 km, the antenna had an almost circular radiation pattern, but effectively also suppressed local interference with its appropriate orientation, which is especially important for those radio amateurs where the level of interference is high. Typical antenna bandwidth is 20 kHz.

Y. Pogreban, (UA9XEX)

Yagi antenna 2 elements for 3 bands

This is a great antenna for the field and for working from home. SWR on all three ranges (14, 21, 28) is from 1.00 to 1.5. The main advantage of the antenna - ease of installation - just a few minutes. We put any mast ~ 12 meters high. At the top there is a block through which a nylon cable is passed. The cable is tied to the antenna and it can be instantly raised or lowered. This is important when hiking, as the weather can change a lot. Removing the antenna is a matter of a few seconds.

Further, only one mast is needed to install the antenna. In a horizontal position, the antenna radiates at large angles to the horizon. If the plane of the antenna is placed at an angle to the horizon, then the main radiation begins to press against the ground and the more, the more vertically the antenna is suspended. That is, one end is at the top of the mast, and the other is attached to a peg on the ground. (See photo). The closer the peg is to the mast, the more vertical it will be and the closer to the horizon the angle of vertical radiation will be pressed. Like all antennas, it radiates in the opposite direction from the reflector. If the antenna is carried around the mast, then the direction of its radiation can be changed. Since the antenna is attached, as can be seen from the figure, at two points, then by turning it 180 degrees, you can very quickly change the direction of its radiation to the opposite.

When manufacturing, it is necessary to maintain the dimensions as they are shown in the figure. We first made it with one reflector - at 14 MHz and it was in the high-frequency part of the 20 meter band.

After adding reflectors at 21 and 28 MHz, it began to resonate in the high-frequency part of telegraph sections, which made it possible to conduct communications in CW and SSB sections. Resonance curves are flat and SWR at the edges is not more than 1.5. We call this antenna Hammock among ourselves. By the way, in the original antenna, Marcus, like hammocks, had two wooden bars 50x50 mm, between which the elements were stretched. We use fiberglass rods, which made the antenna much lighter. The antenna elements are made of an antenna cord with a diameter of 4 mm. Spacers between vibrators made of plexiglass. If you have questions, then write: [email protected]

Antenna "Square" with one element at 14 MHz

In one of his books in the late 80s of the twentieth century, W6SAI, Bill Orr proposed a simple antenna - 1 element square, which was installed vertically on one mast. The W6SAI antenna was made with the addition of an RF choke. The square is made for a range of 20 meters (Fig. 1) and is installed vertically on one mast. In continuation of the last knee of a 10-meter army telescope, fifty centimeters piece of fiberglass is inserted, the shape is no different from the upper knee of the telescope, with a hole at the top, which is the top insulator. It turned out a square with a corner at the top, a corner at the bottom and two corners on extensions on the sides.

In terms of efficiency, this is the most advantageous option for the location of the antenna, which is located low above the ground. The power point turned out to be about 2 meters from the underlying surface. The cable connection unit is a piece of thick fiberglass 100x100 mm, which is attached to the mast and serves as an insulator.

The perimeter of the square is equal to 1 wavelength and is calculated by the formula: Lm = 306.3F MHz. For a frequency of 14.178 MHz. (Lm = 306.3.178) the perimeter will be 21.6 m, i.e. side of the square = 5.4 m. 0.25 wavelength. This piece of cable is a quarter-wave transformer, transforming Rin. antennas of the order of 120 ohms, depending on the objects surrounding the antenna, the resistance is close to 50 ohms. (46.87 ohms). Most of the 75 ohm cable segment is located strictly vertically along the mast. Further, through the RF connector is the main transmission line cable 50 ohms with a length equal to an integer number of half-waves. In my case, this is a segment of 27.93 m, which is a half-wave repeater. This method of powering is well suited for 50 ohm equipment, which today in most cases corresponds to R out. silos of transceivers and the nominal output impedance of power amplifiers (transceivers) with a P-loop at the output.

When calculating the cable length, keep in mind the shortening factor of 0.66-0.68, depending on the type of plastic cable insulation. With the same 50 ohm cable, an RF choke is wound next to the mentioned RF connector. His data: 8-10 turns on a 150mm mandrel. Winding coil to coil. For antennas on the low bands - 10 turns on a mandrel 250 mm. The HF choke eliminates the curvature of the antenna pattern and is a Shut-off Choke for HF currents moving along the cable sheath in the direction of the transmitter. The bandwidth of the antenna is about 350-400 kHz. with SWR close to unity. Outside the passband, the SWR rises strongly. Antenna polarization is horizontal. Stretch marks are made of wire with a diameter of 1.8 mm. broken by insulators at least every 1-2 meters.

If we change the feed point of the square, feeding it from the side, the result is vertical polarization, more preferable for DX. Use the same cable as for horizontal polarization, i.e. a quarter-wave section of a 75 ohm cable goes to the frame, (the central core of the cable is connected to the upper half of the square, and the braid to the bottom), and then a multiple of half a wave of a 50 ohm cable. The resonant frequency of the frame when changing the power point will go up by about 200 kHz. (at 14.4 MHz.), so the frame will have to be slightly lengthened. An extension wire, a cable of about 0.6-0.8 meters can be included in the lower corner of the frame (in the former power point of the antenna). To do this, you need to use a segment of a two-wire line of the order of 30-40 cm.

Antenna with capacitive load at 160 meters

According to the reviews of the operators whom I met on the air, they mainly use an 18-meter structure. Of course, there are 160m enthusiasts who have poles with large sizes, but this is acceptable, probably somewhere in the countryside. I myself personally met a radio amateur from Ukraine, who used this design with a height of 21.5 meters. When compared to transmission, the difference between this antenna and the dipole was 2 points, in favor of the pin! According to him, at longer distances, the antenna behaves remarkably, to the point that the correspondent can not be heard on the dipole, and the pin pulls out the far QSO! He used an irrigation, duralumin, thin-walled pipe with a diameter of 160 millimeters. At the joints, it was covered with a bandage from the same pipes. Fastened with rivets (riveting gun). According to him, when lifting, the structure withstood without question. It is not concreted, just covered with earth. In addition to the capacitive loads, also used as guy wires, there are two more guy kits. Unfortunately, I forgot the call sign of this radio amateur, and I can’t correctly refer to it!

T2FD receiving antenna for Degen 1103

Built a T2FD receiving antenna this weekend. And ... I was very pleased with the results ... The central pipe is made of polypropylene - gray, with a diameter of 50 mm. Used in plumbing under the drain. Inside there is a transformer on the "binoculars" (using EW2CC technology) and a load resistance of 630 ohms (suitable from 400 to 600 ohms). Antenna canvas from a symmetrical pair of "voles" P-274M.

It is attached to the central part with bolts protruding from the inside. The inside of the pipe is filled with foam. Spacer tubes - 15 mm white, are used for cold water (NO METAL INSIDE!!!).

Installation of the antenna, with all the materials, took about 4 hours. And most of the time "killed" to unravel the wire. We “collect” binoculars from such ferrite glasses: Now about where to get them. Such glasses are used on USB and VGA monitor cords. Personally, I got them when disassembling decommissioned monics. Which in cases (revealed into two halves) I would use as a last resort ... Better whole ones ... Now about winding. I wound it with a wire similar to PELSHO - stranded, the lower insulation is made of polymaterial, and the upper one is made of fabric. The total wire diameter is about 1.2 mm.

So, dangles through binoculars: PRIMARY - 3 turns ends on one side; SECONDARY - 3 turns ends on the other side. After winding, we track where the middle of the secondary is - it will be on the other side of its ends. We carefully clean the middle of the secondary and connect it to one wire of the primary - this will be a COLD CONCLUSION. Well, then everything is according to the scheme ... In the evening, I threw the antenna to the Degen 1103 receiver. Everything rattles! True, I didn’t hear anyone on 160 (it’s still early at 7 pm), 80 is boiling, on the “troika” from Ukraine, the guys go well on AM. In general, it works good!!!

From the publication: EW6MI

Delta Loop by RZ9CJ

For many years of work on the air, most of the existing antennas have been tested. When, after all of them, I did and tried to work on a vertical Delta, I realized - how much time and effort I spent on all those antennas - in vain. The only omnidirectional antenna that has brought a lot of pleasant hours behind the transceiver is the vertical Delta with vertical polarization. I liked it so much that I made 4 pieces for 10, 15, 20 and 40 meters. The plans are to make it also at 80 m. By the way, almost all of these antennas *hit* more or less SWR immediately after construction.

All masts are 8 meters high. Pipes 4 meters - from the nearest housing office Above the pipes - bamboo sticks, two bundles up. Oh, and they break, infections. Changed it 5 times already. It is better to tie them in 3 pieces - it will turn out thicker, but it will also last longer. Sticks are inexpensive - in general, a budget option for the best omnidirectional antenna. Compared with the dipole - the earth and the sky. Really *pierced* pile-ups, which was not possible on the dipole. The 50 Ohm cable is connected at the feed point to the antenna web. The horizontal wire must be at a height of at least 0.05 waves (thanks to VE3KF), that is, for a 40 meter band, this is 2 meters.

P.S. Horizontal wire, you need to consider the junction of the cable with the canvas. Changed the pictures a little, the optimum for the site!

Portable HF antenna for 80-40-20-15-10-6 meters

On the site of the Czech radio amateur OK2FJ František Javurek I found an antenna design that is interesting in my opinion, which operates on the bands 80-40-20-15-10-6 meters. This antenna is an analogue of the MFJ-1899T antenna, although the original costs 80 ye, and a home-made one fits into a hundred rubles. Decided to repeat it. This required a piece of fiberglass tube (from a Chinese fishing rod) 450 mm in size, and with diameters from 16 mm to 18 mm at the ends, 0.8 mm varnished copper wire (dismantled the old transformer) and a telescopic antenna about 1300 mm long (I found only a meter Chinese from TV, but built it up with a suitable tube). The wire is wound on a fiberglass tube according to the drawing and taps are made to switch the coils to the desired range. As a switch, I used a wire with crocodiles at the ends. Here's what happened. Switching ranges and the length of the telescope are shown in the table. You should not expect any wonderful characteristics from such an antenna, this is just a hiking option that will have a place in your bag.

Today I tried it at the reception, on the street just sticking it into the grass (at home it didn’t work at all), I received 3.4 districts very loudly at 40 meters, 6 was barely audible. There was no time today to test it longer, as I try to transfer, I will unsubscribe. P.S. You can see more detailed pictures of the antenna device here: link. Unfortunately, there has not yet been an unsubscribe about working on transmission with this antenna. I am extremely interested in this antenna, I will probably have to make and try it in work. In conclusion, I post a photo of the antenna made by the author.

From the site of the Volgograd radio amateurs

80m Antenna

For more than a year, when working on the 80-meter amateur radio band, I have been using the antenna, the device of which is shown in the figure. The antenna has proved to be excellent for long-distance communications (for example, with New Zealand, Japan, the Far East, etc.). The wooden mast, 17 meters high, rests on an insulating plate, which is fixed on top of a metal pipe 3 meters high. The antenna mount is formed by stretch marks of the working frame, a special tier of stretch marks (their top point can be at a height of 12-15 meters from the roof) and, finally, a system of counterweights, which are attached to the insulating plate. The working frame (it is made of an antenna cord) is connected at one end to a system of counterweights, and at the other - to the central core of the coaxial cable feeding the antenna. It has a wave impedance of 75 ohms. The braid of the coaxial cable is also attached to the counterweight system. There are 16 of them, each 22 meters long. The antenna is tuned to the minimum of the standing wave ratio by changing the configuration of the lower part of the frame (“loop”): by approaching or removing its conductors and selecting its length A A ’. The initial value of the distance between the upper ends of the "loop" is 1.2 meters.

It is advisable to apply a moisture-proof coating on a wooden mast; the dielectric for the support insulator must be non-hygroscopic. The upper part of the frame is attached to the mast through: a support insulator. Insulators must also be introduced into the web of stretch marks (5-6 pieces for each).

From the UX2LL website

Dipole 80 meters from UR5ERI

Viktor has been using this antenna for three months now and is very pleased with it. It is stretched like a regular dipole and they respond well to this antenna and from all sides, this antenna only works at 80 m. variable capacitance and measure it and put a constant capacitance to avoid variable capacitance sealing headaches.

From the UX2LL website

Antenna for 40 meters with low suspension height

Igor UR5EFX, Dnepropetrovsk.

The loop antenna "DELTA LOOP", located in such a way that its upper corner is at a quarter-wave height above the ground, and power is supplied to the loop break in one of the lower corners, has a large level of radiation of a vertically polarized wave under a small one, of the order of 25-35 ° angle relative to the horizon, which allows it to be used for long-distance radio communications.

A similar radiator was built by the author, and its optimal dimensions for the 7 MHz band are shown in Fig. The input impedance of the antenna, measured at 7.02 MHz, is 160 ohms, therefore, for optimal matching with a transmitter (TX) having an output impedance of 75 ohms, a matching device was used from two quarter-wave transformers connected in series from coaxial cables 75 and 50 ohms (Fig. 2). The antenna impedance is transformed first to 35 ohms, then to 70 ohms. The SWR does not exceed 1.2. If the antenna is more than 10 ... 14 meters away from the TX, to points 1 and 2 in Fig. you can connect a coaxial cable with a characteristic impedance of 75 ohms of the required length. Shown in fig. dimensions of quarter-wave transformers are correct for cables with polyethylene insulation (shortening factor 0.66). The antenna was tested with an 8W ORP transmitter. Telegraph QSOs with hams from Australia, New Zealand and the USA confirmed the effectiveness of the antenna when working on long distances.

Counterweights (two in a line of quarter-waves for each range) lay directly on the roofing material. In both versions in the bands 18 MHz, 21MHz and 24 MHz SWR (SWR)< 1,2, в диапазонах 14 MHz и 28 MHz КСВ (SWR) < 1,5. Настройка антенны при смене диапазона крайне проста: вращать КПЕ до минимума КСВ. Я это делал руками, но ничто не мешает использовать КПЕ без ограничителя угла поворота и небольшой моторчик с редуктором (например от старого дисковода) для его вращения.

P.S. I made this antenna, but it’s really acceptable, you can work, and work well. I used a device with an RD-09 motor, and made a friction clutch, i.e. so that when the plates are fully withdrawn and inserted, slipping occurs. The discs for the clutch are taken from an old reel to reel tape recorder. A three-section capacitor, if the capacity of one section is not enough, you can always connect another one. Naturally, the whole structure is placed in a moisture-proof box. I'm posting pictures, take a look!

Antenna "Lazy Delta" (lazy delta)

An antenna with a slightly strange name was published in the 1985 Radio Yearbook. It is depicted as an ordinary isosceles triangle with a perimeter of 41.4 m and, obviously, therefore, did not attract attention. As it turned out later, very in vain. I just needed a simple multi-band antenna, and I hung it at a low height - about 7 meters. The length of the supply cable RK-75 is about 56 m (half-wave repeater). The measured SWR values ​​practically coincided with those given in the Yearbook.

Coil L1 is wound on an insulating frame with a diameter of 45 mm and contains 6 turns of PEV-2 wire 2 ... 3 mm thick. HF transformer T1 is wound with MGShV wire on a ferrite ring 400NN 60x30x15 mm, contains two windings of 12 turns. The size of the ferrite ring is not critical and is selected based on the input power. The power cable is connected only as shown in the figure, if it is turned on the other way around, the antenna will not work.

The antenna does not require adjustment, the main thing is to accurately maintain its geometric dimensions. When operating on the 80 m range, compared to other simple antennas, it loses on transmission - the length is too small.

At the reception, the difference is almost not felt. Measurements carried out by G. Bragin's HF bridge ("R-D" No. 11) showed that we are dealing with a non-resonant antenna. The frequency response meter shows only the resonance of the power cable. It can be assumed that a fairly universal antenna (from simple ones) has turned out, it has small geometric dimensions and its SWR is practically independent of the height of the suspension. Then it became possible to increase the height of the suspension to 13 meters above the ground. And in this case, the SWR value on all main amateur bands, except for the 80-meter one, did not exceed 1.4. At eighties, its value ranged from 3 to 3.5 at the upper frequency of the range, so a simple antenna tuner is additionally used to match it. Later it was possible to measure the SWR on the WARC bands. There, the SWR value did not exceed 1.3. The drawing of the antenna is shown in the figure.

V. Gladkov, RW4HDK Chapaevsk

http://ra9we.narod.ru/

Antenna Inverted V - Windom

Radio amateurs have been using the Windom antenna for almost 90 years, which got its name from the name of the American shortwave that proposed it. In those years, coaxial cables were very rare, and he figured out how to power a half-wavelength emitter with a single-wire feeder.

It turned out that this can be done if the antenna feed point (connection of a single-wire feeder) is taken approximately at a distance of one third from the end of the radiator. The input impedance at this point will be close to the wave impedance of such a feeder, which in this case will operate in a mode close to that of a traveling wave.

The idea turned out to be fruitful. At that time, the six amateur bands in use were multiple frequencies (non-multiple WARC bands only appeared in the 70s), and this point turned out to be suitable for them too. Not an ideal point, but quite acceptable for amateur practice. Over time, many variants of this antenna appeared, designed for different ranges, with the general name OCF (off-center fed - with power not in the center).

In our country, it was first described in detail in the article by I. Zherebtsov "Transmitting antennas powered by a traveling wave", published in the journal "Radiofront" (1934, No. 9-10). After the war, when coaxial cables entered amateur radio practice, a convenient power option appeared for such a multi-band radiator. The fact is that the input impedance of such an antenna on the operating ranges is not very different from 300 ohms. This makes it possible to use common coaxial feeders with a wave impedance of 50 and 75 ohms for its power supply through high-frequency transformers with an impedance transformation ratio of 4:1 and 6:1. In other words, this antenna easily entered into everyday amateur radio practice in the post-war years. Moreover, it is still mass-produced for shortwaves (in various versions) in many countries of the world.

It is convenient to hang the antenna between houses or two masts, which is not always acceptable due to the real circumstances of housing both in the city and outside the city. And, of course, over time, there was an option to install such an antenna using just one mast, which is more realistic to use in a residential building. This option is called Inverted V - Windom.

The Japanese shortwave JA7KPT, apparently, was one of the first to use this option for installing an antenna with a radiator length of 41 m. This length of the radiator was supposed to provide it with operation on the 3.5 MHz band and higher HF bands. He used a mast 11 meters high, which is the maximum size for most radio amateurs to install a homemade mast on a residential building.

Radio amateur LZ2NW (http://lz2zk.bfra.bg/antennas/page1 20/index.html) repeated his version of Inverted V - Windom. Schematically, its antenna is shown in Fig. 1. The height of the mast was about the same (10.4 m), and the ends of the emitter were about 1.5 m from the ground. To power the antenna, a coaxial feeder with a characteristic impedance of 50 ohms and a transformer (BALUN) with a coefficient transformations 4:1.

Rice. 1. Antenna circuit

The authors of some versions of the Windom antenna note that it is more expedient to use a transformer with a transformation ratio of 6:1 with a feeder impedance of 50 ohms. But most antennas are still made by their authors with 4:1 transformers for two reasons. Firstly, in a multi-band antenna, the input impedance “walks” within certain limits near the value of 300 Ohms, therefore, on different ranges, the optimal values ​​of the transformation ratios will always be slightly different. Secondly, a 6:1 transformer is more difficult to manufacture, and the benefit from its use is not obvious.

The LZ2NW, using a 38 m feeder, obtained SWR values ​​less than 2 (typical value 1.5) on almost all amateur bands. JA7KPT has similar results, but for some reason it dropped out in SWR in the 21 MHz range, where it was greater than 3. Since the antennas were not installed in a “clear field”, such a fallout on a specific range may be due, for example, to the influence of the environment surrounding it “ gland".

LZ2NW used an easy-to-make BALUN, made on two ferrite rods with a diameter of 10 and a length of 90 mm from the antennas of a household radio. Each rod is wound in two wires with ten turns of wire with a diameter of 0.8 mm in PVC insulation (Fig. 2). And the resulting four windings are connected in accordance with Fig. 3. Of course, such a transformer is not intended for powerful radio stations - up to an output power of 100 W, no more.

Rice. 2. PVC insulation

Rice. 3. Winding connection diagram

Sometimes, if the specific situation on the roof allows, the Inverted V - Windom antenna is made asymmetrical, fixing the BALUN at the top of the mast. The advantages of this option are clear - in bad weather, snow and ice, settling on the BALUN antenna hanging on the wire, can cut it off.

Material B. Stepanov

compactantenna on the main KB bands (20 and 40 m) - for summer cottages, trips and hikes

In practice, many radio amateurs, especially in summer, often need a simple temporary antenna for the most basic KB bands - 20 and 40 meters. In addition, the place for its installation can be limited, for example, by the size of a summer cottage or in a field (on a fishing trip, on a hike - by the river) by the distance between the trees that are supposed to be used for this.

To reduce its size, a well-known technique was used - the ends of the dipole of the 40-meter range are turned towards the center of the antenna and are located along its web. Calculations show that the characteristics of the dipole change insignificantly in this case, if the segments subjected to such a modification are not very long compared to the operating wavelength. As a result, the overall length of the antenna is reduced by almost 5 meters, which under certain conditions can be a decisive factor.

To introduce the second range into the antenna, the author used a method that is called “Skeleton Sleeve” or “Open Sleeve” in the English-language amateur radio literature. Its essence is that the emitter for the second range is placed next to the emitter of the first range, to which the feeder is connected.

But the additional emitter does not have a galvanic connection with the main one. This design can significantly simplify the design of the antenna. The length of the second element determines the second operating range, and its distance to the main element determines the radiation resistance.

In the described antenna for a 40-meter range emitter, mainly the lower (in Fig. 1) conductor of the two-wire line and two segments of the upper conductor are used. At the ends of the line, they are connected to the lower conductor by soldering. The 20-meter range emitter is simply formed by a piece of the upper conductor

The feeder is made of RG-58C/U coaxial cable. Near the point of its connection to the antenna there is a choke - current BALUN, the design of which can be taken from. Its parameters are more than sufficient to suppress common mode current through the outer braid of the cable on the ranges of 20 and 40 meters.

The results of the calculation of antenna patterns. performed in the EZNEC program are shown in fig. 2.

They are calculated for an antenna installation height of 9 m. The radiation pattern for a range of 40 meters (frequency 7150 kHz) is shown in red. The gain at the maximum of the chart on this range is 6.6 dBi.

The radiation pattern for the range of 20 meters (frequency 14150 kHz) is given in blue. On this range, the gain at the maximum of the diagram turned out to be 8.3 dBi. This is even 1.5 dB more than that of a half-wave dipole and is due to the narrowing of the radiation pattern (by about 4 ... 5 degrees) compared to the dipole. The SWR of the antenna does not exceed 2 in the frequency bands 7000…7300 kHz and 14000…14350 kHz.

The author used for the manufacture of the antenna a two-wire line of the American company JSC WIRE & CABLE, the conductors of which are made of steel coated with copper. This ensures sufficient mechanical strength of the antenna.

Here you can use, for example, the more common similar line MFJ-18H250 of the well-known American company MFJ Enterprises.

The appearance of this dual-band antenna, stretched between the trees on the river bank, is shown in Fig. 3.

The only drawback can be considered that it can really be used precisely as a temporary one (in the country or in the field) in spring-summer-autumn. It has a relatively large web surface (due to the use of ribbon cable) so it is unlikely to withstand the load of snow or ice adhering in winter.

Literature:

1. Joel R. Hallas A Folded Skeleton Sleeve Dipole for 40 and 20 Meters. — QST, 2011, May, p. 58-60.

2. Martin Steyer The Construction Principles for “open-sleeve”-Elements. - http://www.mydarc.de/dk7zb/Duoband/open-sleeve.htm.

3. Stepanov B. BALUN for KB antenna. - Radio, 2012, No. 2, p. 58

A selection of broadband antenna designs

Happy viewing!

The design of the indicated antenna was reported to me over the air about 10 ... 15 years ago by a radio amateur V.Voliy (UA6DL), for which I am very grateful to him. The antenna is still working, and I, in principle, am satisfied with its work as a backup antenna. Measured SWR values ​​for a frequency of 1.9 MHz - 1.9; for 3.6 MHz - 1.3; for 7.05 MHz -1.2; for 14.1 MHz -1.4; for 21.2 MHz -1.7; for 28.6 MHz - 1.6. The design of the antenna is shown in Fig.1. The antenna is an ordinary dipole with a beam length of 20.5 m. The antenna is powered by a coaxial cable with a wave impedance of 50 ... 75 ohms. For matching, a broadband matching device on a ferrite ring and a two-wire line with a wave impedance of 300 ohms are used. The two-wire line is made of a KATV television cable 17.7 m long, open at the end. The broadband transformer is made on a ferrite ring of grade 30 ... 50 VCh with an outer diameter of 24 ... 32 mm - depending on the transmitted power (1 cm of the cross section of the core of the ring is capable of transmitting about 500 W without damage). If one ring is not enough, take two or three rings stacked together. The ring(s) are pre-wrapped with PTFE tape. At maximum power, the ring can heat up to 70°C. The transformation ratio of the broadband transformer is 1:4. For the manufacture of a transformer, a PEV 00.8 ... 1.0 wire folded in parallel or a stranded wire in vinyl or fluoroplastic insulation is wound around the ring (it is not afraid of heating). The number of turns is 9 ... 10. After winding, the end of one wire is connected to the beginning of another, forming a midpoint. The broadband transformer is mounted at a distance of 5.9 m from the point of connection of the dipole to the two-wire line. The transformer is protected from moisture by wrapping it with insulating material and varnishing it. The antenna fabric is made of galvanized wire dia. 2 mm, and, apparently, this is the only reason she stood for such a long time in the acid rains of Donbass.

Rice. one

In principle, the antenna arms can be made of 5 ... 8 twisted copper wires of the PEV brand 0.8 mm. Checked - the strength is good. Horizontal wire wave channel. As amateur radio wisdom says, the best high-frequency amplifier in a transceiver (receiver) is an antenna. And it's 100% true! Having a good antenna, you can even work with a home-made transceiver with DX, and vice versa, you cannot "stretch" "weak" correspondents to an expensive imported transceiver and a bad antenna of the same high-frequency correspondents. For these purposes, directional antennas are widely used, since they allow you to concentrate most of the radiated electromagnetic energy in a certain direction, thereby increasing the field strength at the receiving point and reducing interference in other directions, as well as receiving a greater signal level when received from this direction. Of course, the best option is to install a rotating directional antenna, but not all shortwaves can purchase and install such an antenna.

Fig.2

I propose the design of a compromise version of a single-band two-element antenna "Wave Channel" (Fig. 2) with a fixed radiation pattern. The antenna is located in a horizontal plane and has clearly defined directional properties. The design of the antenna is clear from the figure. In the indicated antenna, one active vibrator is a half-wave dipole, the second passive vibrator is the director. The current in the passive vibrator is created by electromagnetic induction by the field of the active vibrator. By changing the length of the passive vibrator and its distance from the active vibrator, it is possible to change the relative phase of the current in it. This is the basis of the principle of concentration of electromagnetic energy in a certain direction. If the current phase in the passive vibrator is such that the resulting field increases in the direction of this vibrator and decreases in the opposite direction, the passive vibrator works as a director. Such an antenna gives a power gain of about 5 dB. The attenuation of interference from radio stations located perpendicular to and behind the direction of the correspondent is also significant, which for this antenna is approximately 15 dB. An antenna made according to the given dimensions, as a rule, does not need to adjust the length of the elements and the distance between them. The antenna fabric is made of a copper cord, copper, galvanized or bimetallic wire dia. 2 mm. If such a wire was not available, you can make a home-made copper cord from 6 ... 8 wires PEV-I or PEV-II 0.7 ... 0.8 mm twisted with a pitch of 2-3 turns per 1 cm. The ends of the cord should be well soldered. Such a homemade cord made of wire is quite durable. Naturally, before installing this antenna, the radio amateur must determine for himself the most interesting direction of radiation (reception). The constructive dimensions of the antenna for each range are given in Table 1.

The antenna sheet itself is attached to stationary supports using a nylon (synthetic) cord, which can be buildings, residential buildings, tall trees, etc. Porcelain nut insulators are used as insulators. However, if such insulators could not be purchased, they can be successfully replaced by home-made insulators made of textolite or getinaks. For their manufacture, an insulating bar is taken (a parallelepiped made of textolite, getinaks, etc.) of suitable sizes, and two holes are drilled in it along the diameter of the wire at an angle of 90 °. Homemade insulators must necessarily work in compression. Insulating strips made of bamboo (pine, getinax or textolite) serve as distance fixers (spacers) between the director and the active element. All cord connections are made only by knitting (knots). To protect against moisture, insulators and spacers are covered with insulating varnish. The design of these insulators is shown in Fig.3.

Rice. 3

Simple efficient antenna G3XAP for 160 and 80 m.

Long-range communication on short waves is carried out due to the so-called sky wave, which is reflected by the ionosphere and can have both vertical and horizontal polarization. When operating on the 160 and 80 m bands, short-wave radio amateurs use both terrestrial and sky waves. That is why it is desirable for this range to have an antenna with vertical radiation. Since a vertical quarter-wave vibrator for the 160 m band is difficult to imagine even in the imagination (its height should be about 40 m!), An antenna for low-frequency bands has to be made in a compromise. Its emitter consists of horizontal and vertical conductors (Fig. 4), or the emitter is placed at an angle to the horizon.

Rice. four

Naturally, the greater the height of the vertical part of the antenna, the higher its efficiency. In addition, the effectiveness of a vertical U4 antenna depends largely on the quality of the ground. It is best to use special grounding - a pin driven into damp ground, a buried sheet of galvanized iron, etc. In extreme cases, metal structures fixed in the ground can be used. It is unacceptable to use plumbing and heating pipes as such grounding, because. in addition to the poor quality of such grounding, there may be strong interference with radio and television reception, as well as burns by high-frequency currents of people when touching pipelines. The proposed antenna in the late 80s was repeated by Yuri, US31VZ, ex RB41VZ. Actively operating SSB on the 160m band, in one year he received QSL from 150 regions of the former USSR. US3IVZ uses this antenna without counterweights. For more efficient operation, it must have counterweights. A 2" steel pipe is mounted on a small support insulator, which can be a porcelain insulator used in electrical installations, or simply by placing a sheet of insulating material under the vertical pipe. To tune the antenna, a variable capacitor C^^ = 500 pF is used, having a gap between the plates of at least 1 ... 2 mm (depending on the power of the RA). The quality of the agreement is judged by the readings of the SWR meter. The input impedance of such an antenna is approximately 60 ohms (depending on the quality of the "ground"), so it is desirable to power it with a coaxial cable with a characteristic impedance of 50 ohms. With careful tuning of the antenna, SWR = 1.1 ... 1.2 is achievable. The dimensions of the antenna are given in Table 2.

Range, m

V. BASHKATOV, USOIZ, Gorlovka, Donetsk region

Literature

1. S.G. Bunin, L.P. Yaylenko. Handbook of a radio amateur-shortwave. - Kyiv, "Technique", 1984.

Capital structures and balcony railings can be successfully used to fix the antenna in cases where the installation of this device on the roof of a building is not possible for some reason. Of course, a HF balcony antenna cannot be compared in efficiency with a basic one, but for many tasks its capabilities will turn out to be quite acceptable. In this article, we will consider in detail a number of issues related to the operation of this kind of antennas, and learn how to do them yourself.

catch the wave

Today, balcony antennas can often be seen on the facades of urban high-rise buildings. Almost all of them are designed to operate in the shortwave range. With the help of such antennas, you can receive radio and television broadcasting signals, they also allow you to use radio stations for amateur or commercial (professional) radio communications. It should be noted that such devices perform radio reception better than transmission.

A self-made balcony HF antenna can always be fixed on the elements of a metal crate, since it has a small weight and small overall dimensions. Only first you need to make sure that the device receives the signal you need clearly enough. The fact is that due to the shielding properties of the building, the balcony antenna works effectively only in some directions, and if your balcony or loggia “looks” in the opposite direction from the signal source, it may be completely useless.

What radio waves are called short? This category includes electromagnetic radiation with a wavelength of 10 to 100 m. These lengths correspond to the frequency range 3 - 30 MHz. A remarkable property of these radio waves is their ability to be reflected from the surface of the earth and the upper atmosphere, with virtually no loss of power. Due to this, the wave, as it were, flows around the surface of the planet, which makes it possible to transmit signals over long distances.

If you notice a deterioration in the quality of communication, do not rush to scrap the antenna. Radio communication on short waves is very sensitive to many factors, among which the main ones are the time of day, weather conditions and the nature of solar activity. These factors affect the reception and transmission of a signal with a balcony antenna, which is inferior in its capabilities to the base one. Another reason for changing the signal level is interference. Waves from the same source reach the antenna along different trajectories, which have, accordingly, different durations. This is the reason for this phenomenon.

We design an antenna for the HF band

Those whose hand reaches for a soldering iron instead of a toothbrush in the morning will probably be interested in how to make a homemade antenna from improvised materials. Primarily, we need a ferrite tube– shielding element of cables from monitors and keyboards. Someone from radio amateurs accidentally discovered that such tubes respond with a reactive impedance within a few hundred ohms to radio signals with a wavelength of just under 100 m. At the same time, a broadband transformer on such tubes demonstrates good frequency response within the shortwave range. These properties of ferrite tubes will help us design a square antenna for a balcony or loggia. To do this, follow the step-by-step instructions:

After installation on the balcony, such a home-made HF antenna demonstrates good reception of signals with a frequency of 14 to 28 MHz.

Read about in our article. It also presents other models, such as floor and ceiling.

If you are wondering: then you will find the answer to it on our website.

Setting up an amateur connection

On the territory of the Russian Federation, two radio frequency bands are open:

— CB range(letters are Latin, the marking is read as "si-bi"), which is shortwave;

— PMR or LPD range, which is ultrashortwave.

They are called open because they can be used without special permission. True, there is one caveat: commercial use of the PMR band is not allowed.

Waves of the CB-band (27 MHz) are able to go around buildings, natural hills and forests. They are characterized by insignificant losses, so the connection of the antenna to the radio station can be done using even cheap cable brands. Installation of base antennas for operation in the CB-band does not contradict the law.

The CB frequencies are characterized by a long-range effect, which is caused by changes in solar activity or in the state of the magnetic field of our planet. It lies in the fact that the signal from a remote source at 10-15 thousand km is received more clearly than from a station operating several kilometers away.

VHF signals (PMR and LPD) are transmitted at a frequency of 433 to 446 MHz. A mobile radio station operating on the LPD band is perfect for organizing communication, for example, between an office and a warehouse. Unlike the equipment "sharpened" for the CB-band, such stations support a multi-channel communication mode and are equipped with very efficient built-in antennas. In addition, LPD stations can be used to organize communication within a building, and their signals can even reach the basement.

Tip: For listening to and communicating with other amateur radio stations, an AM/FM radio with a CB base antenna is best. Such equipment will give you the opportunity to listen to both local stations and foreign broadcasts.