Antennas for 40 meters. We build a HF antenna a guide for beginner radio amateurs

Uncomplicated in design and easy to set up, the antenna was designed to operate in the range of 40 meters. With appropriate correction of the element sizes, it can work on almost any KB range. The antenna belongs to the Crossed Field Antenna (CFA) class - antennas on crossed fields, which, obeying the general laws of physics, differ from the classical ones in the way the radiation wave front is formed. Theoretical prerequisites that served as the basis for the creation of this antenna. developed by Scottish professors M. Heitley and B. Stuart.

When I once again looked through the handbook of shortwavers, the logical circuit presented by K. Rothammel in an article on the transformation of a resonant circuit into a magnetic antenna seemed to me incomplete:

Radio amateur DL1BU visually presented the formation of a magnetic ring antenna. First, a parallel oscillatory circuit is considered (Fig. 1a).

When such a circuit is excited at a resonant frequency, its electrical energy oscillates between a capacitor (electric field) and a coil (magnetic field). Fields of both types are concentrated in this closed system, almost without going beyond its limits.

If the capacitor plates are separated in a closed oscillatory circuit (Fig. 1a) (Fig. 16), the previously closed system turns out to be open and an electric, predominantly near field, appears between the plates. Since the electric field propagates into the outer space. we can say that this oscillatory circuit is an electrical antenna. It corresponds to a highly shortened vibrator with an end capacitance, known as an elementary dipole, or Hertz dipole.

By returning the capacitor plates to their previous position and stretching the turns of the coil so that a ring is formed from its wire, we obtain a magnetic loop antenna (Fig. 1c).

Based on the logic of the CFA, it follows that the frame, which emits mainly the magnetic component, must be equipped with elements capable of emitting the electrical component of the electromagnetic wave. Indeed, it would be logical to use the capacitor formed by the rays to radiate the electrical component of the signal.

The antenna, made in accordance with the electrical circuit shown in fig. 2, according to the distribution of current and voltage (and this has been verified experimentally) corresponds to an inextricable half-wave radiator, and in brief, its operation can be described as follows: The frame, being in the zone of maximum current, forms the magnetic component of the electromagnetic radiation wave, and the antenna beams located in the zone maximum voltage, - the electrical component of the wave. The circuit formed by the internal conductor of the frame and capacitor C1 expands the working frequency band of the antenna, ensures the in-phase nature of these components and, thus, the operation of the antenna in the CFA mode.

The design of the antenna is shown in fig. 3. The frame is made of radio frequency coaxial cable used for the construction of feeder lines in the construction of cellular communication stations. Its name according to the documents is “coaxial cable 1″ flexible LCFS 114-50 JA, RFS (15239211)”. Its outer conductor is made in the form of a corrugated copper pipe with a diameter of about 25 mm, the inner conductor is a copper tube with a diameter of about 9 mm (photo in Fig. 4, below). The black PVC sheath has been removed from the cable, and its outer conductor is covered with several layers of colorless lacquer brand "XB".

I suppose the frame can also be made from a sports hoop or a metal-plastic water pipe. It will only be necessary to place a conductor of a suitable cross section inside, while excluding the possibility of its movement inside the pipe (for example, using insulating washers), and to ensure good galvanic contact with the beams and the capacitor.

It is convenient to use the antenna beams as guy wires when installing it. Initially, the author made them from an antenna cord with a diameter of 3 mm, but after a few rains it turned so black and green that it was replaced by a tinned stranded copper wire of approximately the same diameter without insulation. You can also try to use one wire from the P-274 two-wire field cable.

Capacitor C2, connected to the outer conductor of the frame, is a two-section KPI with a capacity of 12 ... 495 pF from an old broadcasting receiver. To eliminate the influence of the sliding contacts of the rotor, the leads of the stator plates are connected to the frame, while the KPI sections are connected in series, and the capacitance is halved. With the specified beam length, a capacitor capacitance of 50 ... 100 pF is sufficient to tune the antenna into resonance. You can also replace the variable capacitor with a constant one and tune the antenna by selecting the length of the rays. But this method seems to be too troublesome. Since the capacitor is connected in a section with a small voltage, the requirements for its electrical strength are low. Capacitor C1, connected to the inner conductor of the frame, is of the "butterfly" type.

Both capacitors are housed in an appropriately sized airtight plastic box purchased from an electrical store (Figure 5).

The communication loop with the antenna is made of a coaxial cable with a characteristic impedance of 50 ohms, through which it is powered. At the end of the cable and in a place 1900 mm away from it, the outer insulating PVC sheath was removed, and in the middle of this segment, both the sheath and the outer conductor - braid were removed for a length of 10 mm (Fig. 6). The inner conductor is soldered at the end of the cable to the braid. Then this end of the cable is applied to the second section with the outer insulation removed and soldered to it. The resulting loop (ring) is attached to the top of the antenna frame (Fig. 6), which, in turn, is attached to a bamboo pole 5.5 m high using nylon cable ties.

To tune the antenna, a minimum of instruments is required - a transceiver, an SWR meter, a field strength indicator or a neon lamp. The P-loop of the transceiver should be preliminarily tuned to the equivalent load for the maximum output power in the middle of the range of 40 meters (when the antenna is subsequently used with P-loop capacitors, it will be possible to adjust it to some extent).

Connect the antenna to the transceiver, set the rotor of the capacitor C1 to a position corresponding to a capacitance of approximately 10 pF, and use the capacitor C2 to tune the antenna to resonance according to the maximum volume of the received signals. Then measure the SWR of the antenna in the operating frequency band. The minimum SWR in the antenna coincides with the maximum resonance, so there are no tuning problems. For the author, with the indicated dimensions and installation height, the antenna bandwidth exceeds 150 kHz with an SWR of no more than two.

You can also turn on the transceiver for transmission and adjust the antenna according to the maximum indication of the field strength indicator or according to the maximum brightness of the glow of a neon lamp brought to one of the beams.

The antenna has passed a long cycle of climatic tests. In winter, it suffered snowfalls and icing, as well as very serious winds that occur in our area almost every winter. Apparently, the low installation height and the use of a non-metallic (bamboo) mast eliminated problems. The thickness of the icing reached one and a half centimeters. But by the time it became possible to check the performance of the antenna in icing conditions, the insulators had already thawed, although the rest of the part was covered with a solid crust of ice. Oddly enough, this did not affect the performance of the antenna and its parameters.

Trouble came from where I did not expect. Preparing the antenna for winter, I carefully sealed all the seams and joints with silicone sealant. And as it turned out, in vain. Frequent winter thaws and high air humidity caused abundant condensation in the box with capacitors, which over time led to the short circuit of capacitor C2. This was manifested by an increase in SWR to 5 ... 6. The problem was resolved after removing the plugs of the lower holes in the mounting box (by the way, a fair amount of water leaked out). When the box and capacitors were dry, the antenna started working again. I did not put these plugs back, and a similar problem did not arise again.

During experiments with the antenna, it was found that:
1. When switching the antenna beams to the opposite terminals of the loop of the frame, the reception is completely stopped. From this we can conclude that the necessary phase relations are formed for rays only with "its own part of the frame." In other words, the frame is actively involved in the formation of the radiation pattern. As the length of the rays increases, the dip in the diagram (in the horizontal plane) decreases until it disappears completely, and it takes the form of an ellipse elongated in the plane of the antenna. When the antenna is rotated by 90 degrees, the level of the received signal on long-distance routes drops by 1.5 ... 2 points.

2. The angle of vertical radiation of the antenna decreases with increasing length of the beams. The same happens with increasing beam inclination. This is well defined by a decrease in the signal level of near and an increase in the signal level of distant radio stations. When indicated in Fig. 2 the length and angle of the beams of radio stations located closer than three hundred kilometers are not audible or their signals are significantly weakened.

3. An increase in the length of the beams from five to eight meters increases the level of received signals by 6 ... 10 dB, which is somewhat disproportionate and clearly exceeds the increase in the signal that one should expect. The reasons for the disproportionate increase in the signal, apparently, are explained by the formation of the incident wave crest, described in. If so, then the described antenna is the first design to use this effect! The longer the beams (within reasonable limits - no more than 1/4 of the wavelength), the wider the antenna bandwidth and the lower the voltage on the capacitor C2.

4. When the installation height of the frame changes (from two to four meters along the lower edge), the SWR changes from 1.3 to 1. To compensate, it was necessary to increase the capacitance of capacitor C2 by less than 10 pF. Otherwise, the characteristics of the antenna remained the same, except for the decrease in the angle of radiation due to the increased inclination of the beams. It has been experimentally established that an installation height of about 1/8 of the wavelength is sufficient to almost completely eliminate the effect of the earth.

5. The operation of the antenna is not affected by the movement of massive metal objects or people, even at a beam height above the ground of about two meters. It is little susceptible to interference in general, and thunderstorms in particular. It was possible to work without any problems in the midst of a thunderstorm.

The noise level of the antenna, provided that it is located on one of the central streets of the city, does not exceed 4 ... 5 points.

Based on the foregoing, a number of conclusions can be drawn. So, with the indicated low suspension height, the antenna undoubtedly surpasses the wave dipole installed at a height of four meters above the roof of a five-story building.

Based on points 1 and 2 of experimental observations, we can assume that the antenna undoubtedly belongs to the CFA class, in which the radiation flux is formed directly at its elements, and not at a distance, as in classical ones. Apparently, this explains the low sensitivity of the antenna to a change in the height of the installation and the presence of conductive objects directly under the antenna.

Based on paragraph 2, using simple geometric calculations, it can be determined that the angle of maximum radiation of the antenna in the vertical plane is 25 degrees. The multiplication factor for the vertical lobe is negligible compared to the multiplication factor for the main lobe. In this regard, oddly enough, this antenna corresponds to a half-wave dipole set at 1/2X height (for the 7 MHz band, this is 20 m). The optimal elevation angles for the range of 40 meters lie in the range of 12 ... 40 degrees. With a mast height of 5.5 m, there is practically no zenith radiation in the vertical component of the radiation pattern. At the same time, with a mast height of 3.5 m and a beam length of 5 m, parallel to the ground, the antenna allows for both local and relatively long-range radio communications.

The radiation pattern in the horizontal plane does not have pronounced minima, and the antenna allows you to work in all directions.

For more than a year of operation of the antenna, together with a 100 W SDR transceiver, many radio contacts were made with almost all countries of Europe, many countries of Asia and Africa. The most exotic for me are connections with the Azores and the Caribbean, Ceylon, the northern territories of Australia, Brazil, and, of course, Japan.

After installing the antenna at a height of 8m, Indonesia, the USA, Ghana, Venezuela and a rare (for me) connection with a radio station located in the AO-42 locator were added to the above countries.

Alexander GRACHEV (UA6AGW)

Antennas. antennas 2 antennas 3 antennas 4

My first EH antenna

I called it the RDA antenna, because it was designed specifically for communication on the 80m band with nearby RDA areas that are inaccessible on the 20th. In general, the antenna "melee" J

After reading on the sites W0KPH and F6KIM, as well as in the magazine "Radiomir", I was a little sad, because for an antenna on the 80m band you need a plastic pipe with a diameter of 200 mm - where can I get one! But upon further study of the issue, I realized that you can try with a smaller diameter. The market is full of 110 mm plumbing pipes, I found a damaged cheaper J. Cylinders made of brass foil, second-hand wire for coils 1.6mm. I did the calculation of the coils according to the program given by F6KIM, but since the formulas were created for “normal” sizes, the resonant frequency of my antenna turned out to be 1 MHz lower than the calculated L. Unwound part of the turns - now higher than required! Gradually “driven” into the SSB section and went on the air. I already had experience with small-sized antennas, in particular with an annular magnetic frame, so I expected a signal much weaker than, say, from a dipole. In addition, the antenna was in the kitchen on the ground floor of a two-story house with an iron roof. But to my surprise, the signals were 59+10! True, this antenna turned out to be narrow-band, but still not like a frame where “step left - step right” and SWR more than 10. I think that with normal dimensions, the band would be much wider.

After hoisting it on the roof, the frequency jumped up. Adjustment again, though only by shifting the turns of the main coil. Not even at the resonant frequency, the signals from UA9Y, UA9U and UA0A went 59+20. I heard Crimea at 55. What else was noticed. When the antenna is connected ONLY to the MFJ-259 SWR meter, an SWR of 1.1 or even 1.0 is easily achieved. But as soon as the cable braid is connected to the transceiver case, the SWR grows, the frequency moves. I started measuring through an antenna relay connected to the RA case, it seems to have approached “combat” conditions. After this procedure, when adjusting the Pi-loop, a better agreement with the antenna was felt, but the braid still radiated. I passed the cable through the ferrite ring, making two turns - the braid stopped emitting, but it was not possible to achieve a good SWR. I decided to leave the idea with the ring near the antenna, but left it near the transceiver.

After several attempts, we still managed to get an acceptable SWR:

3,600 1,5

3,630 1,0

3,650 1,2

The design of the antenna is shown in Fig.1

Here D = 110 mm. H = 200 mm. Coil L contains 30.7 turns of wire d = 1.6 mm turn to turn (as far as the roughness of wire J allowed). Communication coil - 3 turns. The distance between the coil L and the cylinder is 30 mm, and the coupling coil can move during tuning and eventually came close to a distance of ~ 10 mm to the coil L.

Here are links to sites where I got the information. I don’t like all the explanations of the principle of operation of the antenna, the most common word there is “phasing”, however, it’s not clear why with what and for what reason J. And only the arguments of Lloyd Butler VK5BR (last link) really clarify something.

http://www.qsl.net/w0kph/

http://f6kim.free.fr/sommaire.html

http://www.eheuroantenna.com

http://www.qsl.net/sm5dco

http://www.antennex.com/hws/ws1201/theeh.html

http://www.qsl.net/vk5br/EHAntennaTheory.htm

EH antenna RZ0SP

Pavel Barabanschikov RZ0SP

After reviewing the drawings and diagram of the UA3AIC EH antenna on the Internet, I decided to repeat and made an antenna for the 20-meter range according to the author's drawings. The antenna worked right away. I did not carry out any antenna settings, I only preliminarily calculated the capacitances for the series oscillatory circuit by measuring the inductances of the already assembled antenna without connecting the coaxial cable. The result was somewhat surprised and delighted: the antenna worked. But in my opinion, she was clearly missing something. I listened to stations 3, 4, 6 districts, stations JA1, 7A3, HL, but only 0s, 0Q, 9M, in short, stations of the nearest districts heard me. I already made the second antenna at 80 meters, but with my own modifications (the method for calculating the contours of the antenna is the same). Below is a schematic drawing of the antenna itself. The figure shows: brown - a copper cylinder soldered from the ends (2 pcs.), Red - inductors wound with a wire with a diameter of 2 mm with a pitch of 1 mm - 18 turns (the inductance in the assembled antenna is 12 μH). The coils are inserted into the holes in the fiberglass insulator evenly relative to the geometric center of each of the cylinders, in my case the total diameter of the coil is 50mm (with a cylinder diameter of 100mm and a length of 300mm). The distance between the cylinders (30mm) is filled with polyurethane foam for tightness. Green indicates the feeder RK-75-20, purple - the central core, blue - vibrator λ / 2, turquoise and gray - capacitors of the KSO-250v type. I paid special attention to the phasing of the cylinders and coils, by the way, the capacitances were adjusted taking into account the capacitances introduced into the circuit by the cylinders, but without taking into account the capacitance of the coaxial cable. And accordingly, the beam and the feeder are isolated from the cylinders by fluoroplastic bushings. The antenna is suspended in an L-shape, the main beam length - more than 30 meters - hangs at a height of 10 meters above the ground.

Confidently, at 9-8 points, with small QSB I listened to stations in Belarus, Kamchatka, Moscow region. Somewhat worse than the station of the Krasnodar Territory. During the UB DX contest, QSOs were made with Indian stations YU, Canada, VP2. Of course, it is too early to talk about real results, but I would like to note the good noise immunity of the antenna, especially in industrial QRM conditions.

In the photo in my hands, I have the contour of the antenna element for the 20-meter band, built into the delta loop element, made according to the same principle as the element for the 80-meter band.

Shortened vertical antenna for a range of 40 meters

Currently, many shortwaves use quite powerful (up to 100 W) and compact transceivers. However, for field trips in this case, it is most often necessary to take rather large antennas, which are not easy to transport and install. Therefore, shortened antennas are of particular interest, which, with small sizes, have quite satisfactory efficiency and allow radio communications over medium and long distances with a transmitter power of about 10 and 100 W, respectively.

A rather simple shortened vertical antenna (Fig. 1) for the 40 m range was proposed by the German radio amateur Rudolf Kohl, DJ2EJ. The antenna is quite compact, but, according to the author, it has good parameters. It is a vertical emitter 2.5 m long, the capacitive reactance of which is compensated by the extension coil L1. Counterweights are 6 horizontal conductors 2.5 m long. Coordination of the input impedance of the antenna with the characteristic impedance of the coaxial cable is provided by the coil L2. The antenna is fine-tuned to the operating frequency by changing the inductance of the extension coil L1 using powdered iron rings moving inside the coil. It is enough to select the inductance of the matching coil L2 during the initial tuning of the antenna. For this matching scheme, the galvanic coupling of all components is preferable, which prevents the formation of a static charge on the antenna.

Given that counterweights are not an ideal "ground" and a small RF current flows in them, to prevent this current from flowing to the outer surface of the coaxial cable braid, it is imperative to install an effective cable choke (Fig. 2), located directly under the counterweights. In addition, if a metal mast is used as a reference for the antenna, then it should be electrically "broken" by a dielectric insert.

The efficiency of an antenna depends on the ratio of radiation resistance to loss resistance. A great influence on the efficiency is exerted by losses in the ground in the near field of the antenna and the quality factor of the extension coil. Increased wire resistances and transient resistances of all RF current-carrying connections reduce the efficiency of the antenna.

Losses in dielectrics and insulators are especially pronounced in places where high RF voltage is present, so a short antenna with low radiation resistance (1.6 ohms) and acceptable efficiency requires a low-loss matching network. To do this, it is advisable to combine matching elements and radiating conductors into one electrically and mechanically complete structure.

The antenna, installed at a height of 3 m above the ground, has a gain of -4.6 dBi at a vertical elevation angle of the radiation maximum of 28°, which allows radio communications over medium distances. Long distance radio communications require the antenna to radiate at a low angle to the horizon. To do this (as follows from the graph in Fig. 3), it is required to install the antenna higher.

The design of the matching unit is shown in Figures 4 and 5. The matching circuit and insulating elements form a single unit. A 1 m long round bar of polyester fiberglass is connected to a mounting plate on which six counterweights of 2.5 m each are mounted, an RF connector for connecting a coaxial cable and an L2 matching coil (on a separate mounting bracket). A few centimeters above the mounting plate, an extension coil L1 is fixed on a fiberglass rod. At the upper end of the fiberglass rod there is a holder in which a vertical emitter 2.5 m long is rigidly fixed. Below the mounting panel is a cable RF choke. A thin fiberglass rod is used to move the guide sleeve with three ring cores T157-2 (DHap=39.9; DBHyTp=24.1; h=14.5 mm) of powdered iron stacked together.

The lower end of the fiberglass rod, on which the matching elements are fixed, is inserted into the aluminum mast. With a small antenna installation height, a conical screw is enough to fix the mast in the ground. The lower part of the antenna (counterweights) must be at least 2.5 m above the ground. This installation height provides both a reduction in the influence of losses in the ground on the efficiency of the antenna, and electrical safety (the risk of touching counterweights in transmission mode is reduced). If an "all-weather" antenna is required, then the matching unit should be protected from rain and dampness with a plastic casing.

In the author's version, the counterweights are made of thin-walled copper-plated steel tubes with a diameter of 8 and 4.5 mm, and for a vertical radiator 2.5 m long, two tubes with a diameter of 11.5 and 8 mm are used. To reduce the RF voltage, an aluminum ball 030 mm is installed at the upper end of the emitter. The winding data of the coils are given in the table.

The initial tuning of the antenna consists in selecting the inductance of the extension coil L1 at the selected frequency and the inductance of the coil 12 until the SWR in the cable is close to 1. When operating the antenna, only adjustment of the coil inductance L1 is required.

During the summer months, throughout the day, the antenna, mounted at a height of only 2.5 m above the ground, made it possible to carry out CW and SSB radio communications with amateur radio stations throughout Europe without problems on a 10 watt transmitter. With a 100 watt transmitter and a raised antenna, QSOs were made with DX at the appropriate times. Especially impressive is the clear reception in nature, in places where industrial interference is practically absent. Here in the receiver sounds "the finest primary matter - the purest and highest form of air", as the Greek philosophers called the luminiferous ether!

With a decrease in the inductance of the extension coil L1 and a slight change in the inductance of the coil L2, the antenna can operate in one of the higher frequency KB bands. At the same time, with increasing frequency, its efficiency increases. However, starting from the range of 21 MHz, its directivity pattern in the vertical plane begins to acquire a multi-lobe character.

Based on the article "Kleiner unsymmetrischer vertikaler Dipol", published in the journal CQ DL, No. 8/2008.

Prepared by V. Korneichik. I.GRIGOROV, RK3ZK.

EH antenna "Isotron"

Another antenna of compact dimensions that does not require a matching device. (Clicking on the image on the right will take you to the ISOTRON website (http://www.isotronantennas.com/). For bands 40

and 80m it is made from two strips bent into an inverted “V” shape, the sharp corners of which are then joined together by a spool. The device as a whole is quite compact.

Below is a description of the process of self-manufacturing by a radio amateur of an Isotron antenna for a range of 40m. You can download or view the description

"Secret" antenna

while the vertical "legs" have a length of /4, and the horizontal part - /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. Adjustment consists in adjusting the length, because the surrounding objects and the earth lower the calculated frequency somewhat. It must be remembered that we shorten the end closest to the feeder by  L = ( F / 300,000) / 4 m, and the far end - three times as much.

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.

All-Range Dipole

Shortwave transmitting antennas

INV. VEE at 14MHz coaxial cable

Source - magazine "CQ DL".

Compared to a vertical antenna on long distances, it works the same way, but it makes much less noise and covers the entire range with good SWR

Multi-range single element circle

It is known from publications that the efficiency of a circle (in terms of gain) exceeds square and triangle antennas, so I chose a circle antenna.

The use of a matching device in a multi-band version will not bring the antenna effective operation on the HF bands, since a coaxial type transmission line is used. Between the output of the matching device and the feed point of the antenna, i.e. in cable, the SWR does not change. On the HF bands, the cable will be under a high SWR. Therefore, in reality, this antenna is only for the ranges of 160, 80, 40 meters.

An extension coil of the 160-meter range is made on a dielectric frame with a diameter of 41 mm, 68 turns (winding turn to turn), PEV wire - 1 mm. The inductance is about 87.2 uH. After winding, the coil is treated several times with water-repellent glue and dried at high temperature. Since the grounded mast is an integral part of the antenna here, the metal guys must be broken with insulators. The antenna is tuned using an SWR meter in the places shown in Fig. 3. The most efficient is the Sloer antenna with a length of 1λ (Fig. 4).

L (m) \u003d 936 / F (MHz) x 0.3048.

Side A (m) \u003d 702 / F (MHz) x 0.3048.

Side B (m) \u003d 234 / F (MHz) x 0.3048.

If you install 3-4 such antennas on one mast, then using the antenna switch you can choose different directions of radiation. Antennas that are not involved in the work should be automatically grounded. However, the most efficient antenna design shown is the K1WA system, which consists of five switchable half-wave dipoles. In this system, one dipole is in operation, and the other four, with 3/8λ cable segments open at the ends, form a reflector. Thus, one of the five directions of radiation of the antenna is selected. The gain of such an antenna with respect to a half-wave dipole is about 4 dB. Suppression front-back - up to 20 dB.

Igor Podgorny, EW1MM.

The idea to use rods not only for single verticals arose a long time ago. On their basis, you can make good directional systems for the low bands during field trips. Such a system should be switchable and portable. Restrictions in weight and trouble-free installation turned the project into a task of "not an easy" category, but the "rod direction" of thought allowed me to relax a bit ... As a patient for experiments in nature, the most convenient of the low-frequency bands - 40m was taken.

The choice was made on the developments of colleagues, in terms of phasing 4 verticals, the so-called. "4 SQUARE", which were described by TK5EP and VE3KF. It remained to buy 4 fishing rods 10m long. In addition to the fact that they were unrealistically difficult to find, it also turned out to be an expensive pleasure.

The length of the found fishing rods in the folded state is 1m55cm (the chair is set for scale). The electrical tape is wound at a distance of 64 cm, counting from the bottom edge (more on that later). In the unfolded state, the height of the rod is 9.6m - just right !!

A good testing ground could have been made during RDAC2010, which was suggested by UA9CNV. He agreed without optimism, but the argument that “it’s all the same to go and you have to do something” quickly inclined him in the right direction, especially since his existing non-optimal field antenna at 40m in the form of parallel two highly elongated rhombuses standing on the ground, For several years now, I have not been trusted, for various reasons :)

So, the Collins hybrid coupler on two Micrometals T157-2 rings was taken as a basis. The device diagram is presented below (taken from TK5EP, but something has been corrected):

Transformers T1 and T2 are made on T157-2 rings. The winding is carried out with a bifilar stranded wire D=0.8mm in insulation. The wave impedance of such a line is preferably made with a wave impedance close to 50 ohms. You can check the prepared line by measuring the capacitance of the open line and the inductance of the closed line and by substituting the values ​​into the formula:

Where:
Z - wave impedance of the line, Ohm
L - short-circuited inductance at the end of the line, H
C - open line capacitance, F

Each ring contains 7 turns, evenly distributed around the entire perimeter of the ring. 1 turn is if the wire is passed through the ring 1 time. Initially calculated inductance is 1.13uH.

Capacitors must withstand the power supplied, and also, if possible, have a good TKE NP0, in order to avoid upsetting the device during temperature changes, which can be from -50 to +50 degrees. The simplest solution is to use K15-5 capacitors, but they have a completely obscene TKE. Even capacitors with TKE H20 did not allow for a stable system. Although the system bandwidth is quite large, you need to strive to get out of the situation. Each capacitor for me is made like this: a mica capacitor with a positive TKE is soldered in parallel with K15u-1 - it has a negative TKE. The total TKE of such a battery is almost zero! As a last resort, put several K15-5s in parallel for a voltage of 3kV (up to 1kW), but the capacitance should be nominal at a temperature of -10 degrees, then you can largely avoid changing the coupler tuning frequency with temperature changes. By the way, the last option is not so bad. It will become clear why later.

As a relay, I used SANYOU SZ-S-212L with a winding voltage of 12 volts. If you use SZ-S-224L with a 24 volt winding, you can avoid a large voltage drop on a long control cable.

So, place all the parts in the case and solder all the connections with the shortest possible wires. I got this box:

Such a device can withstand 1 kW!

Now we need to make sure that the formation of phase shifts is correct. To do this, load each of the 4 antenna ports with a load of 100 Ohms, and load the remaining two ports with 51 Ohm resistors (6 resistors in total) and with a two-beam oscilloscope, check the phase matching on the connectors, according to the table below:

Direction	K1	K2	K3	Ant1	Ant2	Ant3	Ant4
Yu (Ant1)
Z (Ant2)
C (Ant3)
B (Ant4)

The direction to the "west" is formed in the absence of control voltage.

For example, here are the waveforms of two ports:

Phase shifter port -90 deg

Signal amplitudes should be as identical as possible!

The next stage is the manufacture of quarter-wave transformers to power each vertical. They are made of a cable with a wave impedance of 75 ohms and Ku>0.75, otherwise their physical length will not be enough to connect to the box. I applied SAT-50 with Ku=0.82. The physical length of such a cable is considered as follows:

1. Wavelength 300/7.1=42.25m

2. Quarter: 42.25/4=10.56m

3. Physical length: 10.56*0.82=8.66m

You cut off a little more from the cable coil and adjust it exactly according to the analyzer - the Ku in the cable passport does not always correspond to reality! I used the AA-330 (having previously switched the 75 Ohm bridge inside) in this switching circuit (the opposite end of the cable must be shorted):

See the desired frequency at the peak of the green graph. If the end is not closed, then the readings will be as follows (it is smeared and in this case it is difficult to adjust the line):

On ready-made cable transformers, in the amount of 4 pieces, we string M600NN 20x12x6 rings at the antenna feed point in the amount of 38 pieces, terminate and turn into a bay:

Now we make the control panel according to the scheme below:

I used a pair of ONTS-VG as connecting connectors.

We wind three or four layers of coarse electrical tape on each fishing rod at a distance of 60-70 cm from the bottom - in order to avoid damage to it on the upper edge of the stake.

We manufacture 8 counterweights 8 m long for each vertical.

We make a load equivalent. Its power depends on the power supplied to the system. At 100 watts, four OMLT-2 200 Ohm resistors connected in parallel are enough.

Well, now everything is ready for going out into nature!

The first thing to do is to find the most flat area. We make markings on it, taking into account the fact that the entire antenna radiates along the diagonals of a square and drive the stakes 40cm deep so as to obtain a distance at each side of the square 1/4L=10.6m.

Next, we lay out on the ground (it is better to raise it as much as possible, but how will it work out) one system of counterweights in the 90-degree sector, according to the diagram below (conditionally only 3 counterweights are shown in each sector:

Counterweight layout

Now, we measure a piece of wire for the vertical canvas. I used one thread from the "vole" P-274 10m long. We attach this segment to the fishing rod in three places with electrical tape.

We raise the fishing rod and fasten it with two clamps so that the wound electrical tape lies just at the upper edge of the corner:

We connect the antenna analyzer to the received system. Our task is to tune this single vertical to the middle frequency of the range, namely 7100 kHz, while it is important to get an impedance of 50 + 0 Ohms at this frequency! If the figure is not obtained, then, depending on the value of the active part of the impedance, counterweights are manipulated (their number, placement in space) until approximately this figure is obtained. The diameters of the emitter conductors and counterweights also contribute to its formation. I got 48+0 ohms. You do this in turn with each vertical, but the length of all four verticals must be made the same! At the same time, already raised verticals can not be removed - just break their connection with something below.

Rods in working position

Now, in the center of the square, we mount the "magic box" and connect to it what is prepared at home: 4 cables to the verticals, load 50 Ohm, feeder, control cable:

Here you go! Now you can test. To begin with, this must be done in a passive way: we measure the SWR - in case of incorrect connections, it will be large. For example, it is worth disconnecting one of the verticals, as the system is so unbalanced that the SWR will be more than 5. In a properly built SWR system<1.3. Впрочем, если не удалось получить приемлемый КСВ при правильной диаграмме, то не думайте, что ошиблись с изготовлением системы - все дело в импедансах полученных вертикалов. Просто примените СУ между магистральным кабелем и "коробочкой".

Now, it is desirable to estimate the resonant frequency of the system (this is not the same as SWR resonance). To do this, you need to measure the power released on the phase shifter equivalent at different frequencies of the range - where it is minimal and is the system tuning frequency. It should be noted here that this power grows towards the edges of the range (less is emitted into the air), but does not exceed 10% of the supplied power. That is, if the input power is 1 kW, then, with a margin, you can put the equivalent of 100 watts. In reality, the indicators are lower and 30 OMLT-2 resistors connected in parallel will cope with the task. As for the SWR band, in the 1 MHz band, the SWR did not exceed 1.2 ..

The calculated antenna diagram is shown below:

The F / B received in my case was 5-6 points. In terms of signal strength, some correspondents later wrote that UA9CNV was the loudest with R9C. Thus, we can say with confidence that the experiment was a success and we can recommend such portable systems for field trips.

For myself, I noted that in RDAC it makes no sense to use 4 verticals - two (west-east) are enough. In this case, the "magic box" is used in the same way, but only antenna ports 4 and 1 are used. In this case, 1/4 power cables must be with a characteristic impedance of 50 ohms and their Ku can be 0.66.

• #1

  Dmitry, you wrote that you set each pin to 50 ohms by changing the position of the counterweights.
  Is that good? After all, the earth may have different conductivity at different times of the year, there may be precipitation, etc. And the counterweights must be grounded one way or another ...

• #2

  There was no talk of grounding counterweights in any way. We are talking only about their placement on the ground in a certain way. In each (any) place, the parameters of the earth do not change so widely even during cataclysms. Therefore, this work needs to be done anyway.

• #3

  Dmitry, good afternoon. You said you found 9.6m rods. But these are carbon fiber rods, not fiberglass (in Moscow, for example, fiberglass is Chinese only up to 6m inclusive). And carbon fiber usually flashes due to electrical conductivity (I encountered it myself. How is it in your case?

• #4

  And one more note. I have been operating the stationary version of the foursquare for more than two years. So, according to all the holy calendar, it is desirable (if they are in the same quantity as yours) to make them raised by a meter - at least one and a half, that is, the feed point of the pins should be raised by this amount. In this case, your reactive field will close almost completely to the counterweights (according to estimates, the losses in the ground will not exceed 5%). Otherwise, a much larger number of counterweights is desirable for the antenna to work well.

• #5

  I won't say anything about rods. However, carbon fiber costs from 10 thousand rubles for such a fishing rod, they cost me much less, so the share of carbon fiber there is negligible. And, judging by the result, which suited everyone, there is no point in paying attention to the material of the fishing rod. I didn't flash it.

  About counterweights - everything is correct. But as it is - 200 radials for a field antenna is too much. And the obvious things about how to make a grounding system and about the desirability of its removal from the ground, in relation to field antennas, can not be discussed. As for the 5% loss, in your reading, I doubt very much, because in order to achieve this figure, it is not enough to raise the counterweights by a meter, it is also necessary to greatly increase their number from the existing one. As a result, the system ceases to be portable.

• #6

  Regarding the material - yes, indeed, since it works, so let it work)). Regarding counterweights, this is what I meant: four radials from each vertical, raised to a height of two meters (so that the wife can spud potatoes in the country))) provide isolation of the reactive field in such a way that if you, in addition to them, spend more, let's say twelve radials along earth - they do not reduce the impedance of a separate vertical, which indicates the effectiveness of these very raised radials, you must agree. Therefore, I work four radials from each vertical, and in principle I succeeded in dixing ... back and forth does not suffer from this. ON4UN in his book about raised counterweights writes the same ... Again, I don’t bother with recommendations, so, a comment for thoughts ...))) Good luck!
  

• #7

  Dmitry, you are saying things that are correct, but obvious. Imagine a vertical field construction with radials raised by 2m. This thing will no longer be portable. Undeniably, raised radials are always better. It should also be noted that they will already need to be configured.

• #8

  Dmitry, what do you think, if 2 vertical triangles are powered by this method, will this system work?

• #9

  Yes, it should. Pay attention to phasing. And yet, for sure, it will be necessary to think about the wave impedance of the supply cables if there is a desire to infinitely bring the SWR closer to 1.

• #10

  radiohamra9da (Friday, 05 October 2012 12:24)

  Dmitry, pay attention to setting up a quarter-wave transformer using an antenna analyzer. The end of the cable must be open. When setting up a half-wave repeater, closed (short-circuited). And look, look at the estimated frequency of 0 reactivity. Then unfortunately some owners of AA-330 are looking for 50 ohms, others SWR =1.

• #11

  Nicholas, hi. How does this contradict what I wrote?

• #12

  Dmitry, if I may have questions about the rings

• #13

  So ask! :)

• #14

  ring question. If not amidon, have you tried something else?

• #15

  ICQ did not set Skype -fedorifk can be transferred there

• #16

  Haven't tried it, but should work. It's just that the size of our rings will be larger in size, all other things being equal.

• #17

  Thank you for reading. There are M2000HM1 diameter-45 mm and the second position M1000HH3 - diameter-120mm, these are large. more cores with LC-5. the inductance of the coils is always 1.13uH.?

• #18

  I'll disturb Dima again. THE AMIDON RINGS COME IN and set everything up. Only the capacitors had to be reduced to 120pF
  since with C \u003d 197pf the resonance is at 6500 and so at 7100. Is the capacitance involved in the phase shift? I feel that somewhere it’s not quite what I wanted. I reread all your correspondence with Barsky, but in practice everything turns out to be more fun

• #19

  Sergey, what did you mean when you wrote "resonance at 6500 .." - how was it measured?

• #20

  Hello Dim Happy New Year! then the phase shift probably changes not so. I tried to work yesterday with an amplifier. There is a diagram in the evening that is clearly visible. But there are doubts, is there a calculation formula?

• #21

  measurements from shek narrower, for clarity

• #22

  Sergey, Happy New Year.
  As I wrote, you can not focus on the SWR readings
  Here is my own quote from the text above: Now, it is desirable to estimate the resonant frequency of the system (this is not the same as the SWR resonance). To do this, you need to measure the power released on the equivalent of the phase shifter at different frequencies of the range.

  Return the PV to its previous form, in which, as you wrote, everything was set up and do not interfere with it anymore.

  Measure the voltage across the dummy and describe the readings.

• #23

  Thanks, I'll take a picture and fix it

• #24

  50% transceiver power first readings C=120/190 F=6.6MHz 5.1/7.3:
  F=6.9-4.0/5.7
  F=7.0 3.2/4.8
  F=7.050 2.7/4.3
  F=7.1 1.9/3.6
  F=7.2 1.4/2.4V
  at the entrance about 30 c. don't know what to think

• #25

  try to put capacity peak 200?

• #26

  1. Carefully reread what is written above.
  2. Make the PV strictly as written and DO NOT touch it anymore. No need to think about fitting containers and other things
  3. Find the point with the minimum power release on the equivalent. Don't look at SWR at all.
  4. If each individual vertical has Rin = 50 + 0 Ohm, then the frequency found will help to understand what needs to be done, namely (in this case) the verticals need to be lengthened.
  5. I doubt that your verticals have just such an impedance, so either achieve it (as I wrote), or leave everything alone, understanding how much power is spent on heating the resistor) and work on the air with pleasure.
  6. PV is balanced when the equivalent is 0 Volts! But for this you need to load its outputs with the right loads. Can someone be sure that 100 Ohm is ideal on the FV connectors?
  7. About "I don't know what to think" - analyze the results! It can be seen that the resonance of the system is out of range (above). Recalculate the received voltages into power and decide how much such losses suit you. I've been aiming for 0.03 watts at resonant frequency, but I don't think that's what you should aim for by spending days tuning. In your situation, just follow step 2 and have fun...

• #27

  Thank you Dim for your time. I think you, too, have been digesting everything for more than one day. Probably not enough theory. Still, if you measure each pin, it’s enough just off. cable from the GO or better from the vertical? measured on each separately not off.

• #28

  Sergey, it is important to have physically the same (length, thickness) verticals, rather than the same Rin. Set up one by tearing the rest off the cable and make the rest look exactly the same. Moreover, in your case, you need to tune them somewhere at 6850 kHz, because. their Rin is strong<50 Ом. Кстати, именно поэтому у них на конце шлейфа >100 ohm. You will get resonance where you want it, but the SWR will be around 1.3. There is nothing terrible in this. It is more important to have a balanced system. If you need a good coordination - put the SU at the entrance to the civil defense. But I have never done that, there is no need for it.

• #29

  Dim, I realized that it was necessary to lengthen them, I don’t know how it would turn out, everything melted, the water stands, we laugh, but it’s still warm, but I’m tinkering like everyone else is normal in winter. in any case, I will unsubscribe. not bad last night was heard working with Korea Venezuela.
  the main thing is already heard well. while I'm at work, I'll do it a little later in the afternoon
  Right now, I'll look at work on an oscilloscope.

• #30

  Dim got to two pins, but parallel. On one at F=7190 R=49 X=24 SW=1.4 Z=52
  on the other at F=6900resonance
  R=51,X=0, Z=51-52om ksv1,2 both are like twins in size, but the first one is next to 4 meters of fence-net and guy lines from the vertical-18 m the second is free, that's how to twist them. solid pipes 6m and 4m at the junction took cm-30 very large takeoff did not even think. I'll put on my boots tomorrow and go to the other two. That's all for now, I'll finish off.

• #31

  Sergey, how are you?

• #32

  Dim hello. I extended the pins to 10.7m. I didn’t have time to measure (resonance) everything melted, I’ll probably have to wait. I work as you said and enjoy it. this option. sorry I can’t calculate it in mana, I just didn’t use it.

• #33

  No need to count - do it and have fun! If I say that the spacing in that design is too small and in general this is a very compromise solution, you will be upset. Therefore, I will not say anything)) But the idea is not bad for those who have problems with the place.

• #34

  Hello Dmitry!
  If I set two verticals at 40 meters. I want the resonance of the system to be at 7.100. What frequency should I tune to a single vertical? To get to the right place almost immediately. but in order to raise and lower the pins as little as possible. If I’m not mistaken, with a system of two verticals, Barsky needs to tune single verticals 60-50 kHz lower than the resonance frequency of the system. And you tuned to 7.100.
  Where is the truth?
  Thank you.
  73.
  ------
  73.

• #35

  True in both cases. It all depends on the execution of the verticals and, ultimately, on the impedance of each vertical. For example, in a system of two dipoles, each of exactly 50+0 ohms, the resonance of the system was exactly where the resonance of each of the dipoles was. I once posted on the forum many years ago the resulting graph. In your case, if you organize a good land, make the pins longer and Alexander wrote correctly. Keep in mind that the SWR at the input to the PV will increase, but don't pay attention to this.
  

• #36

  Dmitry thanks for the answer.
  Another question. The optimal option for counterweights and their length?
  I'm asking for the hiking option.
  I think to put maximum 24 pieces under each pin. Counterweights will be on the ground.
  What length should I take them? 0.1 lambda or 0.25 each.
  Or maybe make 16 pieces of 0.1 lambda for each pin?
  And I don’t want to do a lot (weave a web) and I want the earth to take as little power as possible.
  And in general, the number of counterweights affects F / B?
  And another question. Is it necessary to connect the counterweights to each other, where they intersect, that is, connect them at the point of intersection. And cut off the excess?
  What do you think?
  Thank you.
  73.

• #37

  The best option I think, as I did (that's why I did it). There are many factors. Of course, I want them to be bigger and higher, but all this confusion when moving will start to tire. Many short ones are an option, but there should be a lot of them. If right on the ground, then you can use 0.2L. In general, making land for the vertical is 80% of the work. All laws are known.

  Position the counterweights exactly as in the diagram above - you do not need to dissolve them inside the square - there will be mutual influence. However, for a stationary option, it makes sense to bury and connect them.

• #38

  Hello Dmitry! Everything is clear.
  There is a question-request. You are strong in whom. programs for calculating antennas.
  Do you have experience calculating such vertical dipoles with a capacitive load.
  Power supply through extension coils and there is most likely a communication coil.
  Here's a photo from the company's website.

  http://www.texasantennas.com/index.php?option=com_content&view=article&id=97&Itemid=109

  I read that they can also be powered actively. Can you help with the calculation?
  The height of the dipole is 7.315 meters, if translated from inches.
  We also need the dimensions and data of the coils.

• #39

  I can't help with calculations. All antennas shortened in various ways are not subject to exact calculation. Only the removal of individual impedances at the working height of each element and the use of these data in the calculations. Or a little simpler: only individual impedances and the model should be adjusted to fit them. I thought so 40-2CD and got an excellent result - I posted it here. Spent a lot of time, though, to sort out the details. But then it could be carved out, but now it is not.

• #40

  I re-read what I wrote - somehow it turned out categorically) Oleg - I will always help with advice, but I won’t undertake calculations. Excuse me. There are many nuances and all of them really take time. Ask questions and we can choose a time to discuss. By phone is better.

• #41

  Dmitry understood everything. If anything can be discussed on Skype. But a little later. Works and all sorts of things piled up. hi! 73.

• #42

  Dima, greetings

  If the counterweights are located asymmetrically near the vertical, then the currents in the counterweights are not compensated and the antenna has horizontal polarization with high radiation angles, that is, up to half of the power will be radiated to nowhere, spoiling F / B on short paths.

  For a range of 40m, it is better not to bury the counterweights, but rather raise them together with the power points of the verticals by a couple of meters, with such a raising of the counterweights, losses of the reactive (near) field in the ground will be minimized.

  For this antenna, two oppositely located raised counterweights for each vertical will be sufficient. Counterweights can be placed tangent to the circle formed by four verticals.

  I wonder what resistance R + jX managed to get on ferrite rings dressed on cables? I made such an antenna a long time ago and without rings, but there was a lot of extra cable in quarter-wave segments - due to which I later increased the perimeter of the antenna and raised the gain a little. An extra cable can be wound on rings, it makes sense to make the resistance R or X at least 500 Ohms in order to remove currents from the outside of the braid of quarter-wave segments.

• #43

  Hello Igor.
  He wrote everything correctly, but it is not important for a marching design. First, the symmetry of the counterweights lying on the ground is not so fundamental. Moreover, with this arrangement, we reduce the mutual influence of neighboring grounding systems on the system as a whole. This design usually has 5-6 points F / B. If the counterweights took part in the radiation, such an indicator would not have been achieved on short paths either.

  Secondly, it is natural to raise it better (I wrote about this above in the comments), but the mobility of such a system becomes doubtful.

  Two counterweights here (as in any such system) are not enough. All this will work, but the losses are obvious.

  I did not measure R + jX specifically for these segments, but laid more than 1 kOhm.

• #44

  Dima, greetings

  Modeled a single vertical with two counterweights located in a 90-degree sector on EZNEC. I look at the characteristics of a single element at an elevation angle of 5 degrees (a track of 2500 km or more per jump). Ground type Real/High Accuracy (similar to Nec2).

  Counterweights lie on the ground at a height of 5 cm above the surface. The diagram has a maximum in the direction of stacking counterweights and F / B 2.01 dB. This indicates that more than -2.01 dB of the input power is radiated with horizontal polarization in the direction of the counterweights. The gain of such an antenna in the azimuth maximum is -7.48 dBi.

  I raise the counterweights and the feed point to a height of 2m, I shorten the vertical itself by 2m to reduce the error of additional amplification due to the narrowing of the diagram when the antenna is raised. F/B increased to 2.58 dB gain -5.98 dBi.
  Here, more than -2.58 dB of input power is radiated with horizontal polarization.

  On a raised vertical, instead of a sector, I make two opposite counterweights. Gain -6.48 dB, all power radiated vertically polarized.

  And finally, to assess the losses in the ground, I lower the vertical with two opposite counterweights to the ground, a height of 5 cm above the ground. Gain -7.88 dBi.

  For two opposite counterweights, the difference in antenna gain between those lying on the ground and those raised by 2m was 1.4 dB, mainly this is the power loss of the near field in the ground.

  I make 8 counterweights in the sector of 90 degrees at a height of 5 cm. Gain -7.21 dBi. F/B 2.61 dB. The gain has increased by 0.27 dB compared to the two counterbalances in the 90 deg sector. mainly due to an increase in F / B - that is, due to the emission of a horizontally polarized wave. Losses in the ground compared to two radials in the sector of 90 deg. almost did not decrease.

  Here is the arithmetic. Even 1dB of antenna gain per transmit on the low bands is a huge difference.
  A shortened vertical with two opposing raised weights at a height of 2m beats a full-size vertical with eight sector weights lying on the ground by more than 3 dB in gain (radiated power).

  73,
  Igor

• #45

  I read the correspondence above about the need to adjust the raised radials - they do not need to be adjusted, they are taken of arbitrary but equal length. You can take a length of 7 to 10 meters. Tuning a single vertical to the required frequency is performed by turning on the coil at the power point. I make coils with APV-4 aluminum wire in PVC insulation, 2.2 mm in diameter, bolted with a vertical wire and cable, I make verticals from the same wire. Making and setting up a coil in place for a particular land is easier than trimming and building up counterweights. The frame for the coils is an ordinary plastic sewer pipe with a diameter of 50mm. The coil is fixed on the frame with electrical tape.

• #46

  Igor, a good analysis, but he just says that the balances shifted to the sector redistribute the radiation. In your opinion, how fundamental is the overall increase in antenna gain at an angle of 5 degrees precisely due to horizontal polarization? In other words, which is better: for 5 degrees of elevation, 2dB gain of pure vertical polarization or the same 2dB gain, but with different vertical and horizontal shares? It seems to me that there can be no categorical answer to this, because. all these polarizations at the end point of different correspondents are not taken into account at all. And at different races ... Moreover, it doesn’t matter anymore.

  As for setting up counterweights, I still see two main points:
  1. they must be perfectly symmetrical electrically and geometrically
  2. they must be tuned so that it is as easy as possible for currents to flow into them. An extreme case, for example, symmetrical counterweights of 50 cm each. You will not argue that this is enough.
  3. They should be raised as far as possible. The higher, the less you need.

  Another thing is that for our situations, plus or minus the tram stop will not play a role, because. There are other disturbing factors as well. But you need to take into account.

• #47

  I agree that with equal gain, it does not matter with one polarization or two, radiation is formed, but do not forget that for a single vertical, a circular diagram is lost, that is, with a sectoral arrangement of counterweights, the vertical becomes a directional antenna and the gain is equal only at the maximum of the diagram.

  If you combine 4 verticals with sector counterweights into one antenna system, then each vertical has its own radiation directed in the opposite direction from the center of the system, respectively, the total radiation of the system in the required direction will be less.

  Ideally, oppositely located counterweights should be electrically symmetrical - in this case, the currents flowing oppositely in the counterweights create electromagnetic fields that are completely compensated. In reality, two verticals installed on the ground at a distance of 10 meters with raised counterweights have different input impedance. The ground, even under one vertical, often has different parameters under counterweights, and it is not an easy task to balance currents even in two opposite counterweights - it is necessary to use identical current detectors, possibly assemble a bridge circuit to balance currents when changing the length of a single counterweight. I have not yet mastered this technology in stationary conditions, but there is nothing to say about field ones. The same problem exists when the counterweights are located on the ground, and does not depend on the number of counterweights. If it is not an easy task to balance the currents in two opposite counterweights, then it will be quite difficult to do this for four counterweights.

  Symmetrical counterweights of 50 cm - there is a whole class of verticals with asymmetric power, including commercial products, where the counterweights are close to 50 cm in length. I plan to install a phased array in a summer cottage from a similar type of verticals at 21 MHz within a month, to avoid stretching the counterweights on separate racks.

• #48

  Here the trick is that the main direction of such a vertical is in the forward direction of the entire system, when THIS vertical is connected in the direction to the correspondent. Naturally, in the rear direction, its radiation is minimal, but this is exactly what we need! Although whoever studied it is a mutual influence .. How much better it is, in a sense. I think that this is more important than bothering with unbalancing the system later with a greater influence of the antennas on each other, if the radials were arranged in a circle (their counterweights would inevitably intersect). I think that there is no need to bother with hundredths of a dB - you need to do it and work on the air already. This experience has shown, and your analysis in EZNEC.

  As for unbalanced antennas, I agree, but I wrote about the BEST path for braid currents, and it (the current) is maximum in the center of the dipole, i.e. when both halves are electrically symmetrical.

  I think that at 21MHz it will be better to work 2el yagi at 10m raised than 4SQ :)

• #49

  on 4SQ the light did not converge like a wedge, there are more serious antennas, for example 8 circle. I want to make an 8 circle part but with a large spacing of the halves, the diagram will be with a large gain of the main lobe and ears, especially for working in digital JT65 / JT9, with forward-backward switching. Yagi-type antennas lose to phased verticals in the speed of changing direction. And 8 circle phasing is much simpler than 4SQ - as with two phases of verticals, it is performed by a conventional LC chain with a two-beam oscilloscope, it usually takes 15..20 minutes. For the west-east field option, this is a simple and effective antenna.

• #50

  Well.. 8 - need even more space. About the speed of rotation, perhaps the only plus))

• #51

  the variant of the half of the 8-circle range of 40m west-east fit into the remaining two-thirds of the plot of 10 acres, the remaining third is occupied by the house and all sorts of buildings. Two raised counterweights per vertical. I dismantled it a month ago, in August-September of last year, the antenna gave about 700 Japanese in CW - about 99% of those who gave a general call on the band in my transmission window worked out.

• #52

  So I mean: give this 2/3 of the site ... This is a feat ;-)

• #53

  counterweights and power points are raised 2m above the ground, a garden and a garden under the antenna, all cables, counterweights and verticals are mounted on racks, only racks in the ground - everything else is above your head, respectively, only the area under the racks is occupied on the ground (I use steel corners, fiberglass tubes , fishing rods). Racks only interfere with mowing the grass on the lawn - you have to go around.

• #54

  Hi all! I plan to put a vert.ant at 40 meters in the spring. Question on counterweights - what material is copper or galvanized wire? how much will the efficiency of the antenna decrease when galvanized?

• #55

  Copper, maybe aluminum. No need for galvanizing. How much - no one thought, but you can independently put the material in MMANA and see the reaction, subject to restrictions, of course.

• #56

  Dmitry thanks for the answer. My antenna is a 7 MHz Goncharenko directional antenna. After reading all the comments and opinions, I came to the conclusion that for this antenna system, the counterweights must be made as shown in the figure above (in the antenna itself, according to the recommendation, it is not clear how to properly position the counterweights - after all, there are 8 counterweights under the active radiator, at least 4 more under 4 passive ones and they all intertwine one under the other creating a web and it is not known how it affects the efficiency of the antenna). I will do as you recommend to spread the pr. outward from the middle. The counterweights and the antenna itself will be at a height of 2.5 m from the ground. Dimitri, am I right? Basil.

• #57

  If the height of the system is 2.5m, then 1 counterweight is sufficient, with the so-called. losses. But it's even better to make them in pairs and set them up in pairs, like a dipole - this will be an excellent system and a clearly vertical polarization.

• #58

  Dmitry thanks for the answer. If we make dipoles, then again the question arises of placing counterweights - under the active e element 8 pr. 10.4 evenly spaced around the circumference, but how then to place the pr. under the passive elements? From the central radiator to the pass. elem. 6 meters. It turns out that they intersect. Basil.

• #59

  I do not want to go into the details of an incomprehensible design, the link to which you did not give, but try to place the counterweights so that each vertical has two symmetrical counterweights and they are configured like a dipole. If not, then start with one counterweight.

• #60

  Dmitry good evening. Link to the antenna http://dl2kq.de/ant/3-30.htm. There are options in the placement of counterweights. 1 is the same as in your version. 2- make counterweights dipoles (there is an antenna analyzer). 3-place counterweights under passive elements. in a circle without electrically connecting with other counterweights. There is an empty place under the antenna so you can work all summer to get the result. I need work at low angles and had good gain. Vasily.

• #61

  Well, then it's strange that you ask me questions, and not DL2KQ. In this design, it would be desirable to preliminarily conduct a simulation. I do not rule out that there is some optimal arrangement of counterweights. So far, I'm in favor of pairs: one inside to the vibrator, the second outside the system - from it. And if you have such conditions, then, it seems to me, you would be better off considering using SpitFire, but in 4 directions.

• #62

  Thanks Dmitry for the answer. There is still time to model and reflect on the antenna. Thanks for communication. Basil.

• #63

  http://www.egloff.eu/index.php/en/

  Dmitry, what is the simplification?
  Maybe like the author?

• #64
• #65

  Dmitry, hello!
  Your calculated data L = 1.13 μH, C = 226 pF.
  From the formula we find Z = 70 Ohm.
  Did you really count for 70 ohms or there is an error somewhere in the source data.
  For Z=75 ohm L=1.13 uH C=200pF
  

• #66

  Sergey, I don’t know by what formula you calculated 70 ohms, but I can assume that according to the one given in the text FOR LINES. It is impossible for her. Secondly, Cx is initially calculated based on R line = 100 Ohm, and Lx - from 50. Everything is fine, do as it is written ;-)

• #67
• #68

  You have to do exactly what I wrote. If L=1.25, then you need to rewind the turns to 1.13. The ratio of L and C in the circuit should be exactly the same for this R. If you want to calculate for another R (but you didn’t mention it), then you need to recalculate the entire system, yes.

• #69

  It happens when the impedances of the verticals are low (shortened verticals), it is really possible to recalculate the system not at 50, but at 35 ohms, for example. Potmo agree on the entrance and that's it. You just need to understand that the R lines on the ring are the same as before, about 100 Ohms, and the SWR lines will still be increased.

• #70

  In general, C=1000000/(2PFXc), where Xc=100 ohms (in a 50 ohm system), C is in pF.
  L=X/(2ПF), where X=50 Ohm, L in µH, F in MHz.

• #71

  Thanks, Dmitry.
  There is no special need to recalculate for another resistance. By the spring, slowly began to make an antenna for the exit. I will customize according to your recommendations.

• #72

  After winding the transformer, does it make sense to fix the turns, for example, with hot glue or varnished cloth?

• #73

  Enough plastic clamps at the beginning and end

Every radio amateur dreams of having directional antennas on his radio station. This problem is especially relevant for low-frequency bands, where full-sized directional antennas, such as Yagi, are already so impressive in size that it is not even possible to install such a structure. And on top of that, obtaining permission to install such simply huge antennas is far from an easy task.

Attention is presented to the variant of the directional antenna for the range of 40 meters (7 MHz). This antenna has the following features:

• Gain 4.2 dbi
• Angle of maximum radiation in the vertical plane 33 degrees
• Forward/backward ratio 24 db (4 points on S meter)
• Beam width (DN) in azimuth (at -3db level) 192 degrees

The antenna is shown in fig. 1

Rice. 1

It is an inclined half-wave dipole with a length of 19.65 m from a copper wire of 1.5-2 mm. The wire can be used in PVC insulation, but in this case, the shortening coefficient of the wire in PVC should be approximately 0.96, i.e. the dipole will have a total length of 18.87 m. An integral part of this antenna is a 13.7 m high and 40 mm diameter melalic tube mounted on an insulator. At the bottom, the pipe is connected to a copper wire-radial 9-10 m long. This length is not very critical in the direction of increase, because the excess length will be compensated by capacitor C. The wire is ordinary copper Ø 1-1.5 mm. At the junction point of the pipe and the radial, a variable capacitance capacitor with a maximum capacitance of 300-400 pF is included in the gap, which is the tuning organ of this antenna.

From the figure it becomes clear that the pipe with a radial is a passive reflector with a total length of 22.7 m. In this case, the condenser acts as a shortening element for the reflector. The active vibrator is an inclined dipole. There is no need to explain how the reflector of any antenna works. From above, the pipe is extended to a height of 15.2 m by a dielectric insert. It can be polyethylene, PVC, fiberglass or any other dielectric, such as wood.

An inclined dipole is attached to the end of the insert. The lower end of the dipole can be located above the ground / roof at a distance of 1 m. It is known that there is always a maximum voltage at the ends of the dipole, so for safety reasons it is better to place it higher, say 2.5 meters, but then you will have to increase the overall height of the entire antenna. You can make the following option - bend the lower end of the dipole towards the mast and secure it with a rope to the mast. In this case, safety is ensured against accidental contact with the dipole during transmission. Such an alternative option loses a little in gain (about 0.5 dbi), but it reduces the radiation angle in the vertical plane by 1 degree,

The antenna is best tuned for maximum signal suppression. The gain of the antenna during the tuning of the capacitor remains almost constant, but the suppression changes very much. Therefore, for tuning, it is best to use a generator with a vertical rod antenna spaced at least 3-4 lambdas from the antenna. When modeling, a capacitance of 260 pF is obtained. In reality, this value may be different. After finishing the tuning, the capacitor can be replaced with a permanent ceramic one with the required number of kvar. The antenna pattern in the vertical plane is shown in Fig. 2

Rice. 2

It can be seen that the antenna receives and emits signals over a wide range of angles. This is good for both short runs and transatlantic ones. On fig. 3 shows the azimuth antenna pattern. The red color shows the vertical component of the antenna radiation, blue (eight) - horizontal, and black - the total antenna pattern.

Rice. 3

When connecting the antenna power cable, the cable core should be connected to the upper half of the dipole and the braid to the bottom. The input impedance of the dipole in this antenna is 110 ohms. If you feed the antenna with a 75 ohm cable, we get SWR = 1.47. For those who want to more carefully match the dipole to the cable, a ¼ wave length of 75 ohm cable connected to the dipole can be used. At the other end of such a transformer cable there will be an impedance of 51.1 ohms, so you can already connect a 50 ohm cable of any length to it.

Now some recommendations for those who want to make such an antenna with DN in 4 directions. In this case, 4 similar dipoles and 4 individual radials, 9 meters for each direction, will naturally be needed. But in this case, when working in a particular direction, the remaining dipoles should not take part. To do this, you need to turn off the cables that are not working at the moment (braid and core) with the help of a relay, right at the power point of each dipole. Thus, each dipole will consist of two segments of approximately 10 meters, which do not resonate and therefore do not affect the operation of the antenna. It is also desirable to disable non-working radials. If the radials are not turned off, the antenna loses its gain to 3.1 dbi and its forward / backward ratio decreases to 15-16 dB.

The antenna can be used for other ranges by scaling its dimensions. Such an antenna will be useful for DX hunters, diplomas, contestmen.

A. Barsky VE3XAX ex VA3TTT

73!

In radio communication, antennas are given a central place, in order to ensure its best, radio communication, action, antennas should be given the closest attention. In essence, it is the antenna that carries out the radio transmission process itself. Indeed, the transmitting antenna, fed by a high-frequency current from the transmitter, converts this current into radio waves and radiates them in the right direction. The receiving antenna, on the other hand, performs the reverse conversion - radio waves into a high-frequency current, and already the radio receiver performs further conversions of the received signal.

For radio amateurs, where you always want more power, to communicate with possibly more distant interesting correspondents, there is a maxim - the best amplifier (HF), this is an antenna.

To this club of interests, while I belong somewhat indirectly. There is no amateur radio call sign, but it's interesting! You can’t work for the program, but listen, get an idea, that’s it, please. Actually, this occupation is called radio surveillance. At the same time, it is quite possible to exchange with a radio amateur whom you heard on the air, receipt cards of the established sample, in the slang of radio amateurs QSL. Acknowledgments of reception are also welcomed by many HF broadcasting stations, sometimes encouraging such activities with small souvenirs with radio station logos - it is important for them to know the conditions for receiving their radio broadcasts in different parts of the world.

The observer's radio receiver can be quite simple, at least at first. The antenna, on the other hand, is a construction that is unlike more cumbersome and expensive, and the lower the frequency, the more cumbersome and expensive - everything is tied to the wavelength.

The bulkiness of antenna structures is largely due to the fact that at a low suspension height, antennas, especially for low-frequency bands - 160, 80.40 m, work poorly. So it is the masts with guy wires that provide them with bulkiness, and lengths of tens, sometimes hundreds of meters. In a word, not particularly miniature pieces. It would be nice to have a separate field for them near the house. Well, that's how lucky.

So, an asymmetric dipole.

Above is a diagram of several options. The MMANA mentioned there is a program for modeling antennas.

The conditions on the ground turned out to be such that the variant of two parts 55 and 29m comfortably fit. It stopped on it.
A few words about the radiation pattern.

The antenna has 4 petals, "pressed" to the canvas. The higher the frequency - the more they "cling" to the antenna. But truth and empowerment have more. So on this principle

it is possible to build completely directional antennas, which, however, have, in contrast to the “correct” ones, not a particularly high gain. So you need to place this antenna taking into account its DN.

The antenna on all ranges indicated on the diagram has SWR (standing wave ratio, a very important parameter for the antenna) within reasonable limits for HF.

To match an asymmetric dipole - aka Windom - you need a SPTDL (broadband transformer on long lines). Behind this terrible name lies a relatively simple design.

Looks like this.

So what has been done.
First of all, I decided on strategic issues.

I made sure that the basic materials are available, mainly, of course, a suitable wire for the antenna web in the proper amount.
Decided on the place of suspension and "masts". The recommended hanging height is 10m. My wooden mast, standing on the roof of the firewood shed, turned in the spring with falling frozen snow - I didn’t wait, it’s not a pity, I had to clean it up. It was decided so far to hook one side of the roof ridge, while the height will be about 7m. Not much, of course, but cheap and cheerful. It was convenient to hang the second side on a linden tree standing in front of the house. The height there turned out to be 13 ... 14m.

What was used.

Tools.

Soldering iron, of course, with accessories. Power, watts, that way forty. Tool for radio installation and small metalwork. Whatever is boring. A powerful electric drill with a long drill bit for wood was very useful - let the coaxial drop cable through the wall. Definitely an extension cord. Used hot glue. Work at height is ahead - it is worth taking care of suitable strong ladders. It helps a lot to feel more confident, away from the ground, a safety belt - like fitters on poles. Climbing up, of course, is not very convenient, but you can already work “there”, with both hands and without much concern.

Materials.

The most important thing is the material for the canvas. I used a "vole" - a field telephone wire.
Coaxial cable to reduce how much you need.
A few radio components, a capacitor and resistors according to the scheme. Two identical ferrite tubes from high-frequency filters on cables. Ties and fasteners for thin wire. A small block (roller) with an ear-mount. A suitable plastic box for the transformer. Ceramic insulators for the antenna. Nylon rope of suitable thickness.

What was done.

First of all, I measured (seven times) pieces of wire for the canvas. With some margin. Cut off (once).

I took up the manufacture of a transformer in a box.
Picked up ferrite tubes for the magnetic circuit. It is made of two identical ferrite tubes from filters on monitor cables. Now old CRT monitors are simply thrown away and it is not particularly difficult to find "tails" from them. You can ask around with friends, for sure, someone may be gathering dust in attics or in the garage. Good luck if there are familiar system administrators. In the end, in our time, when switching power supplies are everywhere and the struggle for electromagnetic compatibility is serious, there can be many filters on cables, moreover, such ferrite products are vulgarly sold in electronic component stores.

Matched identical tubes are folded in the manner of binoculars and fastened with several layers of adhesive tape. The winding is made of a mounting wire of the maximum possible cross section, such that the entire winding fits in the windows of the magnetic circuit. The first time it did not work out and I had to proceed by trial and error, fortunately, there are very few turns. In my case, there was no suitable section at hand and I had to wind two wires at the same time, making sure that they did not overlap in the process.

To obtain a secondary winding, we make two turns with two wires folded together, then pull each end of the secondary winding back (in the opposite direction of the tube), we get three turns with a midpoint.

From a piece of rather thick textolite, a central insulator is made. There are special ceramic ones specifically for antennas, of course it is better to use them. Since all laminates are porous and, as a result, are very hygroscopic, so that the antenna parameters do not “float”, the insulator should be thoroughly impregnated with varnish. I applied oil glyptal, yacht.

The ends of the wires are cleaned of insulation, passed through the holes several times and thoroughly soldered with zinc chloride (soldering acid flux) so that the steel veins are also soldered. Soldering points are very thoroughly washed with water from flux residues. It can be seen that the ends of the wires are pre-threaded into the holes of the box where the transformer will sit, otherwise you will then have to thread all 55 and 29 meters into the same holes.

I soldered the corresponding transformer leads to the cutting points, shortening these leads to a minimum. Before each action, do not forget to try on the box, so that everything fits later.

From a piece of textolite from an old printed circuit board, I sawed a circle to the bottom of the box, there are two rows of holes in it. Through these holes, a coaxial drop cable is attached with a bandage of thick synthetic threads. The one in the photo is far from the best in this application. This is a television with foam insulation of the central core, the “mono” core itself, for screw-on TV connectors. But there was a trophy bay available. Applied it. Circle and bandage, well impregnated with varnish and dried. The end of the cable is pre-cut.

The rest of the elements are soldered, the resistor is made up of four. Everything is filled with hot-melt adhesive, probably in vain - it turned out hard.

Ready-made transformer in the house, with "outputs".

In the meantime, a fastening to the ridge was made - there are two boards at the very top. Long strips of roofing steel, stainless steel eyelet 1.5mm. The ends of the rings are welded. On the strips along a row of six holes for self-tapping screws - distribute the load.

Block prepared.

I didn’t get ceramic antenna “nuts”, I used vulgar rollers from old wiring, fortunately, they are still found in old village houses for demolition. Three pieces on each edge - the better the antenna is isolated from the "ground", the weaker signals it can receive.

The applied field wire is interwoven with steel strands and can withstand stretching well. In addition, it is intended for laying in the open air, which is also quite suitable for our case. Radio amateurs quite often make canvases of wire antennas from it, and the wire has proven itself well. Some experience of its specific application has been accumulated, which first of all says that you should not bend the wire too much - the insulation bursts in the cold, moisture gets on the cores and they begin to oxidize, in that place, after a while, the wire breaks.