According to numerous requests from radio amateurs-travelers and radio amateurs-dacha residents, in this article we will again talk about walking radio expeditions and will continue to study the possibilities of conducting communications on HF, with minimal weight of the antenna system and a simple design. These antennas were tested with the FT-817 transceiver and MFJ-902 tuner.
...about the wire
First, let's decide what properties the wire from which we will make the antenna should have. The first material, in our case, copper is suitable for creating an effective emitter. And not just a copper wire, but an insulated copper wire. The diameter of this wire should be in the range of 1.5 - 2.5mm. A thinner one will break in a strong wind, and a thicker one will be unreasonably heavy. Please note that the wire should not be very soft and not too hard. Now, you can easily select a wire that meets these conditions.
In the photographs you see three successful options for insulated wires. The second question we have to answer is: “How long should the wire be?” This depends on the HF band, but we need an antenna that can operate with sufficient efficiency on all bands. Let's decide on priorities; radio expeditions primarily choose the 7 MHz and 14 MHz bands. Therefore, we will focus on them to get good parameters. Based on this, we can immediately say that the length of the wire should be no less than 9 and no more than 21 meters. Why is that so, do you understand? We need an antenna without counterweights, which means its length should be ½λ or 1λ. A longer one means excess weight, a shorter one means low efficiency.
If during a radio expedition you plan to work mainly on 14 - 28 MHz, take a piece of wire about 10 meters long. With it you will be able to conduct near and far QSOs at 14 MHz and work quite well at 18 - 28 MHz, and if necessary, switch to 7 MHz, although the efficiency here will not be high, but nevertheless it is ¼λ at 7 MHz and it will work.
With a piece of wire about 20 meters long, you can effectively operate on 14 and 7 MHz, as well as all HF bands up to 29 MHz and make local QSOs on 3.6 MHz. I note that if conditions allow you to hang one end of the wire at a height of at least 10 meters, then at 3.6 MHz you will be able to make long-distance communications.
...how are we going to hang it?
We have decided on the wire and its length, now we need to figure out how to hang a piece of wire in space in order to work as efficiently as possible with low power (and we use FT-817) on HF bands.
The classic option for mounting antennas of this type is an inclined beam. We hook one end to a tree at the maximum possible height (usually 3 - 6 meters). You see this option in the picture. There is a very slight directionality towards the tilt. To increase the efficiency of the antenna, with a wire length of 20 meters, you can use an additional mast from a fishing rod or stick, as shown in the picture.
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In the middle picture on the right, the direction of radiation will have a slight maximum in the opposite direction of the beam tilt. In the lower picture on the left, in the 14 MHz range, we get a pressed lobe and a slight gain. At 7 MHz, this option works like a half-wave vibrator, only powered at the edge and not at the center.
The peculiarity of all these antennas (based on a long wire) is that they simultaneously radiate both horizontal and vertical polarization. With a low transmitter power (5W), this is rather a minus, because the radiation is unevenly divided between polarizations and accordingly decreases in each of them.
Can beam antennas compete with dipoles and rods? Yes and no, it’s easier and faster to hang a beam than a dipole. The efficiency of the beams is slightly lower (at the same suspension height), only due to the emission of two polarizations. In real life, under certain conditions, this may not be noticeable.
An important advantage of the beams is multi-range, without any switching or switching. In conclusion, a few general tips to help you get the most out of your antenna system:
If you go to a known place where there is a support on which you can lift one end of the wire, then you don’t need to take the mast (rod).
UA6HJQ
http://ua6hjq.qrz.ru/ant/kusok.htm
Only an antenna-feeder device can be connected directly to the transmitter, the input impedance of which ensures its normal operation. Most antennas currently used by shortwave radio amateurs are powered using a coaxial cable with an SWR close to 1 (usually no more than 2). The antenna coupling devices available in the output stages of tube power amplifiers provide the possibility of matching with such antenna-feeder devices, i.e., transmitting maximum output power to the antenna. Transistor power amplifiers may not have controls for adjusting the coordination with the antenna and require connecting to them a feeder with an SWR of no more than 1.1 ... 1.2. Therefore, between an antenna-feeder device with a large SWR and any transmitter and between a transmitter designed to work with a specific matched feeder (for an active load of 50 or 75 Ohms) and any antenna-feeder device, it is necessary to include a matching device. To control the settings of the matching device between the transmitter and the antenna input, turn on the SWR meter, as shown in Fig. 3.11. In this case, the SWR meter must operate at full transmitter output power. Connection diagram of the matching device Fig. 3.11 differs from the diagrams usually given in textbooks on antenna-feeder devices, where a matching device is connected between the antenna and the feeder, ensuring minimal SWR, and therefore losses in the feeder. In the practice of shortwave radio amateurs, matching the antenna with the feeder is achieved by connecting it to the antenna feed points, the resistance between which is close to the characteristic impedance of the feeder, or by using simple impedance transformers between the antenna and feeder. And in some types of HF amateur radio antennas, feeders are used that are mismatched with the antenna; radio amateurs call such structures antennas powered by a standing wave. When these antennas use feeder lines with low losses (for example, overhead two-wire balanced lines), the efficiency of the antenna-feeder device, as shown above, remains quite high.
A matching device that transforms the input impedance of the antenna into an active impedance close to 75 Ohms also turns out to be useful during reception. It ensures optimal matching of the receiver input circuit (usually designed to connect a coaxial cable with a characteristic impedance of 50 ... 75 Ohms) and, therefore, the implementation of the full sensitivity of the receiver.
The matching devices used by radio amateurs (in particular, those described below) are also useful for improving the filtering of spurious emissions from the transmitter and are a good means of protecting against interference with television reception.
Figure 3.12 shows a diagram of a universal matching device designed to work with an asymmetrical antenna-feeder device (antenna fed by a coaxial cable, antenna of the “long wire” type with grounding, etc.). This device provides the ability to match a transmitter designed for a load of 50 or 75 Ohms with an antenna having an active component of the input resistance from 10 to 1000 Ohms and an inductive or capacitive reactive component of the input resistance up to 500 Ohms. Operating frequency range 1.8 ... 30 MHz, input power up to 200 W. If it is necessary to work with the full power allowed for amateur HF radio stations, the device parts (Fig. 3.12) must be designed to operate at HF voltages reaching 3000 V - the gaps between the C1 plates must be at least 3 mm, the distances between the switch contacts must be at least 10 mm. When working with lower powers or when matching antennas fed by coaxial cables with an SWR of no more than 3, it is sufficient to use C1 with a gap of 0.5 mm (double variable capacitor from old broadcast receivers) and conventional ceramic biscuits switches. Coil L1 is wound on a ceramic frame with a diameter of 50 mm with copper wire with a diameter of 1.5 mm. Counting from the end connected to XS1, it contains: two turns with a pitch of 5 mm, the end connected to XS1, it contains: two turns with a pitch of 5 mm, two turns with a pitch of 5 mm, three turns with a pitch of 3 mm, three turns with a pitch of 3 mm, five turns with a pitch of 3 mm, five turns with a pitch of 3 mm and five sections of seven turns with a pitch of 2 mm.
Switch SA1 regulates the inductance of coil LI. Switch SA2 changes the matching circuit: in the one shown in Fig. 3.12 position SA2 capacitor C1 is connected between the transmitter output and the housing, and L1 - between the transmitter output and the antenna.
This ensures matching of antennas with low input impedance.
In the next (according to the diagram) position SA2, capacitor C1 is connected between the antenna and the housing, and L1 remains connected between the transmitter output and the antenna. In this position SA2, matching of antennas with high input impedance is ensured. In the last (according to the circuit) position SA2, elements C1 and L1 are connected in series between the transmitter output and the antenna, which makes it possible to compensate for the reactive component of the antenna input impedance without transforming its active component.
Scheme Fig. 3.12 can also be used to connect a transmitter with an unbalanced output (for coaxial cable) with a symmetrical antenna. To do this, a balun transformer must be connected between XS2 and the antenna (Fig. 3.13).
Connector XS1 is connected to the antenna output of the matching device according to the diagram in Fig. 3.12, and the wires of the symmetrical cable feeding the antenna are connected to XS2 and XS3. Transformer T1 can be made on a toroidal ferrite magnetic core with a magnetic permeability of 70 ... 200, with a diameter of about 100 mm and a cross-section of at least 2 cm2. The winding is made with fluoroplastic insulated wire, the wire cross-section is at least 2 mm2 (you can use copper wire passed into a fluoroplastic tube or copper wire with any other high-frequency insulation rated for voltages up to 3000 V). The winding is made with two wires twisted with a pitch of about 15 mm per crossing of the wires. The number of turns is 2x15, the beginning of one wire is connected to the end of the other, forming a grounded tap of the transformer. It should be taken into account that depending on the input impedance of the antenna and the core material, the number of turns T1 may have to be selected. In addition, the magnetic circuit of the transformer can become a source of losses and nonlinear distortions of the signal, leading to the appearance of side components of the transmitter signal in the antenna when they are absent at its output.
More reliable for working with a symmetrical antenna is a matching device assembled according to the diagram in Fig. 3.14. Like the device shown in Fig. 3.12, it is designed for input power up to 200 W in the range 1.8 ... 30 MHz. Capacitor C1 must have a gap between the plates of at least 0.5 mm, and C2 - at least 2 mm. Coil L1 is wound on a ceramic frame with a diameter of 50 mm. From the grounded tap, a copper wire with a diameter of 1.2 mm is wound in both directions. The first ten turns on both sides of the outlet are wound with a pitch of 4 mm, then another 20 turns with a pitch of 3 mm. A tap is made from each turn of the coil (it is convenient to make it in the form of a petal made of copper foil). The taps are located evenly around the circumference of the coil so that it is easy to connect leads connecting L1 to the devices to any of them. On each band, it is necessary to select the position of the connections of connectors XS2 and SS3 (connection with the antenna) and the inductance L1 with short-circuiting jumpers. In this case, the number of feeder connection positions and the number of active turns on each side L1 of the grounded tap must be the same. The tap connecting capacitor C1 to L1 regulates the connection of the matching device with the transmitter. Capacitor C1 tunes the communication circuit with the transmitter into resonance, and C2 tunes the communication circuit with the antenna. Performing adjustments to matching devices made according to the diagrams in Fig. 3.12 and 3.14 are labor-intensive. The large number of adjustment elements available in these circuits makes it possible to achieve a SWR close to 1 in the cable going to the transmitter. Since with an arbitrary position of the adjustment elements of the matching devices, the transmitter may be sharply mismatched with the load, adjustment of the matching with the antenna must begin at a minimum transmitter power .
You can use on each band (or only on bands where the SWR in the antenna feeder is large) separate matching devices made on the basis of the circuits in Fig. 3.12 and 3.14.
The device assembled according to the diagram in Fig. 3.14, allows you to achieve matching of the transmitter with the antenna with different settings of the connection adjustment taps of the transmitter and the antenna. If the connection on both sides is weak, the filtering effect of the matching device increases, but its efficiency decreases during the operation of the radio station, you can select the optimal connections in the matching device, in which the manifestation is completely absent spurious radiation with sufficiently small losses in it. When working with a symmetrical antenna, it is advisable to check whether its symmetrical power supply is actually provided. To do this, measure the RF voltages on the feeder wires in relation to the transmitter housing. Their values must be equal with an accuracy of no worse than ±2%.
In amateur practice, it is not so often possible to find antennas in which the input impedance is equal to the feeder, as well as the output impedance of the transmitter. In the vast majority of cases, it is not possible to detect such a correspondence, so it is necessary to use specialized matching devices. The antenna, feeder, and transmitter output are part of a single system in which energy is transmitted without any loss.
How to do it?
To implement this rather complex task, you need to use matching devices in two main places - this is the point where the antenna connects to the feeder, and also the point where the feeder connects to the transmitter output. The most widespread today are specialized transforming devices, ranging from oscillatory resonant circuits to coaxial transformers, made in the form of individual sections of coaxial cable of the required length. All of these matching devices are used to match impedances, ultimately minimizing overall transmission line losses and, more importantly, reducing out-of-band emissions.
Resistance and its features
In the vast majority of cases, the standard output impedance in modern broadband transmitters is 500 m. It is worth noting that many coaxial cables used as a feeder also have a standard characteristic impedance of 50 or 750 m. If we consider antennas for which If matching devices can be used, then depending on the design and type, the input impedance has a fairly wide range of values, ranging from several Ohms to hundreds and even more.
It is known that in single-element antennas the input impedance at the resonant frequency is practically active, and the more the transmitter frequency differs from the resonant one in one direction or another, the more reactive component of an inductive or capacitive nature will appear in the input impedance of the device itself. At the same time, multi-element antennas have an input impedance at the resonant frequency, which is complex due to the fact that various passive elements contribute to the formation of the reactive component.
If the input impedance is active, it can be matched to the impedance using a specialized antenna matching device. It is worth noting that the losses here are practically insignificant. However, immediately after a reactive component begins to form in the input resistance, the matching procedure will become more and more complex, and it will be necessary to use an increasingly complex matching device for the antenna, the capabilities of which will allow compensation for unwanted reactivity, and it should be located directly at the point nutrition. If the reactivity is not compensated for, it will negatively affect the SWR in the feeder and also significantly increase the overall losses.
Is it necessary to do this?
An attempt to fully compensate for reactivity at the lower end of the feeder is unsuccessful, since it is limited by the characteristics of the device itself. Any changes in the transmitter frequency within narrow sections of amateur bands will ultimately not lead to the appearance of a significant reactive component, as a result of which there is often no need for its compensation. It is also worth noting that the correct design of multi-element antennas also does not provide for a large reactive component of the existing input impedance, which does not require its compensation.
On the air, you can quite often find various disputes about what role and purpose the matching device for the antenna (“long wire” or other type) has in the process of matching the transmitter with it. Some have high hopes for it, while others simply consider it an ordinary toy. That is why you need to correctly understand how an antenna tuner can really help in practice, and where its use will be unnecessary.
What it is?
First of all, you need to correctly understand that the tuner is a high-frequency impedance transformer, with the help of which, if necessary, it will be possible to compensate for reactance of an inductive or capacitive nature. Let's look at an extremely simple example:
A split vibrator, which at the resonant frequency has an active input impedance of 700 m, and at the same time it is used with a transmitter having an input impedance of about 500 m. Tuners are installed at the output of the transmitter, and in this situation they will be used for any antenna (including “long cable”) matching devices between the transmitter and the feeder, coping with their main task without any difficulty.
If you subsequently tune the transmitter to a frequency that differs from the resonant frequency of the antenna, then reactivity may appear in the input impedance of the device, which will subsequently begin to appear almost instantly at the lower end of the feeder. In this case, the matching device “P” of any series will also be able to compensate for it, and the transmitter will again achieve consistency with the feeder.
What will happen at the output where the feeder connects to the antenna?
If you use a tuner exclusively at the output of the transmitter, then in this case it will not be possible to provide full compensation, and various losses will begin to occur in the device, since there will be incompletely accurate matching. In such a situation, it will be necessary to use another one, connecting between the antenna and the feeder, which will completely correct the situation and provide reactivity compensation. In this example, the feeder acts as a matched transmission line of arbitrary length.
One more example
A loop antenna, which has an active input impedance of about 1100 m, must be matched to a 50 Ohm transmission line. The transmitter output in this case has a value of 500 m.
Here you will need to use a matching device for the transceiver or antenna, which will be installed at the point where the feeder is connected to the antenna. In the vast majority of cases, many hobbyists prefer to use RF transformers of various types equipped with ferrite cores, but in fact a more convenient solution would be to make a quarter-wave coaxial transformer, which can be made from a standard 75-ohm cable.
How to implement this?
The length of the cable segment used should be calculated using the formula A/4 * 0.66, where A is the wavelength, and 0.66 is the shortening factor used for the vast majority of modern coaxial cables. The matching devices of HF antennas in this case will be connected between the 50-ohm feeder and the antenna input, and if they are rolled into a coil with a diameter of 15 to 20 cm, then in this case it will also act as a balancing device. The feeder will be fully automatically matched with the transmitter, as well as if their resistances are equal, and in such a situation it will be possible to completely abandon the services of a standard antenna tuner.
Another variant
For such an example, we can consider another optimal matching method - using a multiple of a half-wave or a half-wave coaxial cable with, in principle, any characteristic impedance. It is connected between the tuner located near the transmitter and the antenna. In this case, the input impedance of the antenna, which has a value of 110 Ohms, is transferred to the lower end of the cable, after which, using an antenna matching device, it is transformed into a resistance of 500 m. In this case, the transmitter is fully matched with the antenna, and the feeder is used as a repeater .
In more severe situations, when the input impedance of the antenna does not correspond to the characteristic impedance of the feeder, which, in turn, does not correspond to the output impedance of the transmitter, two HF antenna matching devices are required. In this case, one is used at the top to match the feeder to the antenna, while the other matches the feeder to the transmitter at the bottom. At the same time, there is no way to make some kind of matching device with your own hands, which can be used alone to match the entire circuit.
The emergence of reactivity will make the situation even more difficult. In this case, matching devices for the HF ranges will significantly improve the matching of the transmitter with the feeder, thus ensuring a significant simplification of the operation of the final stage, but you should not expect more from them. Due to the fact that the feeder will be mismatched with the antenna, losses will appear, so the efficiency of the device itself will be reduced. An activated SWR meter installed between the tuner and the transmitter will ensure that the SWR is fixed at 1, but this effect cannot be achieved between the feeder and the tuner, since there is a mismatch.
Conclusion
The benefit of the tuner is that it allows you to maintain the optimal transmitter mode while operating with an unmatched load. But at the same time, the efficiency of any antenna (including the “long wire”) cannot be improved - the matching devices are powerless if it is mismatched with the feeder.
The P-circuit, which is used in the output stage of the transmitter, can also be used as an antenna tuner, but only if there is an operational change in the inductance and each capacitance. In the vast majority of cases, both manual and automatic tuners are resonant loop tunable devices, regardless of whether they are factory assembled or someone decided to make a matching device for the antenna with their own hands. Manual ones have two or three regulating elements, and they themselves are not efficient in operation, while automatic ones are expensive, and for operation at serious power their cost can be extremely high.
Broadband matching device
Such a tuner satisfies the vast majority of variations in which it is necessary to ensure matching of the antenna with the transmitter. Such equipment is quite effective when working with antennas used on harmonics, if the feeder is a half-wave repeater. In this situation, the antenna input impedance differs on different bands, but the tuner allows easy matching with the transmitter. The proposed device can easily operate at transmitter powers of up to 1.5 kW in a frequency band from 1.5 to 30 MHz. You can even make such a device yourself.
The main elements of the tuner are an HF autotransformer on the deflection system of the TV UNT-35, as well as a switch designed for 17 positions. It is possible to use conical rings from the UNT-47/59 or any other models. The winding contains 12 turns, which are wound into two wires, with the beginning of one being combined with the end of the second. In the diagram and in the table, the numbering of turns is continuous, while the wire itself is multi-core and enclosed in fluoroplastic insulation. In terms of insulation, the diameter of the wire is 2.5 mm, providing taps from each turn, starting from the eighth, if you count from the grounded end.
The autotransformer is installed extremely close to the switch, and the connecting conductors between them must have a minimum length. It is possible to use a switch with 11 positions if the design of the transformer with a not so large number of taps is maintained, for example, from 10 to 20 turns, but in such a situation the resistance transformation interval will also decrease.
Knowing the exact value of the antenna input impedance, you can use such a transformer in order to match the antenna with a 50 or 750 m feeder, using only the most necessary taps. In such a situation, it is placed in a special moisture-proof box, after which it is filled with paraffin and placed directly at the antenna feed point. The matching device itself can be made as an independent structure or be included in a special antenna-switching unit of a radio station.
For clarity, the mark mounted on the switch handle shows the amount of resistance that corresponds to this position. To ensure full compensation of the reactive inductive component, it is possible to subsequently connect a variable capacitor.
The table below clearly states how resistance varies depending on the number of turns you make. In this case, the calculations were carried out based on the resistance ratio, which is a quadratic function of the total number of turns made.
Antenna matching devices. Tuners
ACS. Antenna tuners. Scheme. Reviews of branded tuners
In amateur radio practice, it is not so often possible to find antennas in which the input impedance is equal to the characteristic impedance of the feeder, as well as the output impedance of the transmitter. In most cases, such a correspondence cannot be detected, so it is necessary to use specialized antenna matching devices. The antenna, feeder and transmitter output (transceiver) are part of a single system in which energy is transmitted without any loss.
All-range matching device (with separate coils)
Variable capacitors and biscuit switch from R-104 (BSN unit).
In the absence of the specified capacitors, you can use 2-section ones from broadcast radio receivers, connecting the sections in series and isolating the body and axis of the capacitor from the chassis.
You can also use a regular biscuit switch, replacing the rotation axis with a dielectric one (fiberglass).
Details of tuner coils and components:
L-1 2.5 turns, AgCu wire 2 mm, coil outer diameter 18 mm.
L-2 4.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-3 3.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-4 4.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-5 3.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-6 4.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-7 5.5 turns, PEV wire 2.2 mm, outer. coil diameter 30 mm
L-8 8.5 turns, PEV wire 2.2 mm, outer. coil diameter 30 mm
L-9 14.5 turns, PEV wire 2.2 mm, outer. coil diameter 30 mm
L-10 14.5 turns, wire PEV 2.2 mm, outer. coil diameter 30 mm.
It was urgent to launch 80 and 40 m in someone else's house, there was no access to the roof, and there was no time to install an antenna.
I threw a vole a little over 30 m from the third floor balcony onto a tree. I took a piece of plastic pipe with a diameter of about 5 cm and wound about 80 turns of wire with a diameter of 1 mm. I made taps at the bottom every 5 turns, and at the top every 10 turns. I assembled this simple matching device on the balcony.
I hung a field strength indicator on the wall. I turned on the 80 m range in QRP mode, picked up a tap on top of the coil and used a capacitor to tune my “antenna” to resonance according to the maximum of the indicator readings, then picked up a tap at the bottom to the minimum of the VAC.
There was no time, and therefore I didn’t put up biscuits. and “ran” along the turns with the help of crocodiles. And the entire European part of Russia responded to such a surrogate, especially at 40 m. No one even paid attention to my vole. This is of course not a real antenna, but the information will be useful.
RW4CJH info - qrz.ru
Matching device for low frequency range antennas
Radio amateurs living in multi-storey buildings often use loop antennas on the low frequency bands.
Such antennas do not require high masts (they can be stretched between houses at a relatively high altitude), good grounding, a cable can be used to power them, and they are less susceptible to interference.
In practice, a triangle-shaped frame is convenient, since its suspension requires a minimum number of attachment points.
As a rule, most shortwave operators tend to use such antennas as multi-band antennas, but in this case it is extremely difficult to ensure acceptable matching of the antenna with the feeder on all operating bands.
For more than 10 years I have been using a Delta antenna on all bands from 3.5 to 28 MHz. Its features are its location in space and the use of a matching device.
Two vertices of the antenna are fixed at the roof level of five-story buildings, the third (open) is on the balcony of the 3rd floor, both of its wires are inserted into the apartment and connected to a matching device, which is connected to the transmitter with a cable of arbitrary length.
At the same time, the perimeter of the antenna frame is about 84 meters.
The schematic diagram of the matching device is shown in the figure on the right.
The matching device consists of a broadband balun transformer T1 and a P-circuit formed by a coil L1 with taps and capacitors connected to it.
One of the options for transformer T1 is shown in Fig. left.
Details. Transformer T1 is wound on a ferrite ring with a diameter of at least 30 mm with a magnetic permeability of 50-200 (non-critical). The winding is carried out simultaneously with two PEV-2 wires with a diameter of 0.8 - 1.0 mm, the number of turns is 15 - 20.
The P-circuit coil with a diameter of 40...45 mm and a length of 70 mm is made of bare or enameled copper wire with a diameter of 2-2.5 mm. Number of turns 13, bends from 2; 2.5; 3; 6 turns, counting from the left according to the L1 output circuit. Trimmed capacitors of the KPK-1 type are assembled on studs in packages of 6 pieces. and have a capacitance of 8 - 30 pF.
Setup. To configure the matching device, you need to connect the SWR meter to the cable break. On each band, the matching device is adjusted to a minimum SWR using adjusted capacitors and, if necessary, selecting the position of the tap.
Before setting up the matching device, I advise you to disconnect the cable from it and set up the output stage of the transmitter by connecting an equivalent load to it. After this, you can restore the connection between the cable and the matching device and perform final adjustments to the antenna. It is advisable to split the 80-meter range into two sub-bands (CW and SSB). When tuning, it is easy to achieve an SWR close to 1 on all ranges.
This system can also be used on the WARC bands (you just need to select the taps) and on 160 m, accordingly increasing the number of coil turns and the perimeter of the antenna.
It should be noted that all of the above is true only when the antenna is directly connected to the matching device. Of course, this design will not replace the “wave channel” or “double square” at 14 - 28 MHz, but it is well tuned on all bands and removes many problems for those who are forced to use one multi-band antenna.
Instead of switchable capacitors, you can use KPE, but then you will have to tune the antenna every time you switch to another band. But, if this option is inconvenient at home, then in field or hiking conditions it is completely justified. I have repeatedly used reduced delta options for 7 and 14 MHz when working in the field. In this case, two peaks were attached to trees, and the supply was connected to a matching device lying directly on the ground.
In conclusion, I can say that using only a transceiver with an output power of about 120 W for operation on the air without any power amplifiers, with the described antenna on bands 3.5; 7 and 14 MHz have never experienced any difficulties, while I usually work on a general call.
S. Smirnov, (EW7SF)
Design of a simple antenna tuner
Antenna tuner design from RZ3GI
I offer a simple version of an antenna tuner assembled in a T-shape.
Tested together with FT-897D and IV antenna at 80, 40 m. Built on all HF bands.
Coil L1 is wound on a 40 mm mandrel with a pitch of 2 mm and has 35 turns, a wire with a diameter of 1.2 - 1.5 mm, taps (counting from the ground) - 12, 15, 18, 21, 24, 27, 29, 31, 33, 35 turns.
Coil L2 has 3 turns on a 25 mm mandrel, winding length 25 mm.
Capacitors C1, C2 with Cmax = 160 pF (from the former VHF station).
The built-in SWR meter is used (in FT - 897D)
Inverted Vee antenna on 80 and 40 m - built on all bands.
Yuri Ziborov RZ3GI
Tuner photo:
A great many designs and schemes are known under the name “Z-match”, I would even say more designs than schemes.
The basis of the circuit design from which I based is widely distributed on the Internet and offline literature, it all looks something like this (see right):
And so, looking at many different diagrams, photographs and notes posted on the Internet, the idea was born to me to build an antenna tuner for myself.
My hardware magazine was at hand (yes, yes, I am a follower of the old school - old school, as young people say) and on its page a diagram of a new device for my radio station was born.
I had to remove a page from the magazine “to get to the point”:
It is noticeable that there are significant differences from the original source. I did not use inductive coupling with the antenna with its symmetry; for me, an autotransformer circuit is enough because There are no plans to power the antennas with a balanced line. For ease of setup and monitoring of antenna-feeder structures, I added an SWR meter and a Wattmeter to the overall scheme.
Having finished calculating the circuit elements, you can begin prototyping:
In addition to the housing, it is necessary to manufacture some radio elements; one of the few radio components that a radio amateur can make himself is an inductor:
And here is what happened as a result, inside and outside:
The scales and markings have not yet been applied, the front panel is faceless and not informative, but the main thing is that it WORKS!! And this is good…
R3MAV. info – r3mav.ru
Matching device similar to Alinco EDX-1
I borrowed this antenna matching device circuit from the branded Alinco EDX-1 HF ANTENNA TUNER, which worked with my DX-70.
C1 and C2 300 pf. Air dielectric capacitors. Plate pitch 3 mm. Rotor 20 plates. Stator 19. But you can use dual KPIs with a plastic dielectric from old transistor receivers or with an air dielectric 2x12-495 pf. (as in the picture)
You ask: “Won’t it sew?” The fact is that the coaxial cable is soldered directly to the stator, and this is 50 Ohms, and where should the spark jump with such a low resistance?
It is enough to stretch a line 7-10 cm long from the capacitor with a “bare” wire, and it will burn with a blue flame. To remove static, the capacitors can be bypassed with a 15 kOhm 2 W resistor (quote from “Power amplifiers of the UA3AIC design”).
L1 - 20 turns of silver-plated wire D=2.0 mm, frameless D=20 mm. Bends, counting from the top end according to the diagram:
L2 25 turns, PEL 1.0, wound on two ferrite rings folded together, dimensions D outer = 32 mm, D int = 20 mm.
Thickness of one ring = 6 mm.
(For 3.5 MHz).
L3 has 28 turns, and everything else is the same as L2 (For 1.8 MHz).
But, unfortunately, at that time I could not find suitable rings and did this: I cut rings out of plexiglass and wound wires around them until they were filled. I connected them in series - it turned out to be the equivalent of L2.
On a mandrel with a diameter of 18 mm (you can use a plastic sleeve from a 12-gauge hunting rifle), 36 turns were wound turn to turn - this turned out to be an analogue of L3.
Matching device for delta, square, trapezoid antennas
Among radio amateurs, a loop antenna with a perimeter of 84 m is very popular. It is mainly tuned to the 80M band and with a slight compromise it can be used on all amateur radio bands. This compromise can be accepted if we are working with a tube power amplifier, but if we have a more modern transceiver, things will no longer work there. A matching device is needed that sets the SWR on each band, corresponding to the normal operation of the transceiver. HA5AG told me about a simple matching device and sent me a short description of it (see picture). The device is designed for loop antennas of almost any shape (delta, square, trapezoid, etc.)
Short description:
The author tested the matching device on an antenna, the shape of which is almost square, installed at a height of 13 m in a horizontal position. The input impedance of this QUAD antenna on the 80 m band is 85 Ohms, and on harmonics it is 150 - 180 Ohms. The characteristic impedance of the supply cable is 50 Ohms. The task was to match this cable with the antenna input impedance of 85 - 180 Ohms. For matching, transformer Tr1 and coil L1 were used.
In the range of 80 m, using relay P1, we short-circuit coil n3. In the cable circuit, coil n2 remains switched on, which, with its inductance, sets the input impedance of the antenna to 50 Ohms. On other bands P1 is disabled. The cable circuit includes n2+n3 coils (6 turns) and the antenna matches 180 Ohms to 50 Ohms.
L1 – extension coil. It will find its application on the 30 m band. The fact is that the third harmonic of the 80 m band does not coincide with the permitted frequency range of the 30 m band. (3 x 3600 KHz = 10800 KHz). Transformer T1 matches the antenna at 10500 KHz, but this is still not enough, you also need to turn on the L1 coil and in this connection the antenna will already resonate at a frequency of 10100 KHz. To do this, using K1, we turn on relay P2, which at the same time opens its normally closed contacts. L1 can also serve in the 80 m range, when we want to work in the telegraph area. On the 80 m band, the antenna resonance band is about 120 kHz. To shift the resonance frequency, you can turn on L1. The switched on coil L1 noticeably reduces the SWR at the 24 MHz frequency, as well as at the 10 m band.
The matching device performs three functions:
1. Provides symmetrical power to the antenna, since the antenna web is isolated at HF from the ground through transformer coils Tr1 and L1.
2. Matches the impedance in the manner described above.
3. Using coils n2 and n3 of transformer Tr1, the antenna resonance is placed in the corresponding, permitted frequency bands by range. A little more about this: If the antenna is initially tuned to a frequency of 3600 kHz (without turning on the matching device), then on the 40 m band it will resonate at 7200 kHz, on 20 m at 14400 kHz, and on 10 m at 28800 kHz. This means that the antenna needs to be extended in each range, and the higher the frequency of the range, the more extension it requires. Just such a coincidence is used to match the antenna. Transformer coils n2 and n3, T1 with a certain inductance, the more the antenna extends, the higher the frequency of the range. In this way, on 40 m the coils are extended to a very small extent, but on the 10 m band they are extended to a significant extent. The matching device puts a correctly tuned antenna into resonance on each band in the region of the first 100 kHz frequency.
The positions of switches K1 and K2 by range are indicated in the table (right):
If the input impedance of the antenna on the 80 m range is set not in the range of 80 - 90 Ohms but in the range of 100 - 120 Ohms, then the number of turns of coil n2 of transformer T1 must be increased by 3, and if the resistance is even higher, then by 4. The parameters of the remaining coils remain unchanged changes.
Translation: UT1DA source - (http://ut1da.narod.ru) HA5AG
Elements of the SWR meter: T1 - antenna current transformer wound on a ferrite ring M50VCh2-24 12x5x4 mm. Its winding I is a conductor threaded into a ring with antenna current, winding II is 20 turns of wire in plastic insulation, it is wound evenly around the entire ring. Capacitors C1 and C2 are of the KPK-MN type, SA1 is any toggle switch, PA1 is a 100 μA microammeter, for example, M4248.
Elements of the matching device: coil L1 - 12 turns PEV-2 0.8, internal diameter - 6, length - 18 mm. Capacitor C7 - type KPK-MN, C8 - any ceramic or mica, operating voltage of at least 50 V (for transmitters with a power of no more than 10 W). Switch SA2 - PG2-5-12P1NV.
To set up the SWR meter, its output is disconnected from the matching circuit (in point A) and connected to a 50-ohm resistor (two MLT-2 100 Ohm resistors connected in parallel), and a CB radio station operating for transmission is connected to the input. In the direct wave measurement mode - as shown in Fig. 12.39 position SA1 - the device should show 70...100 µA. (This is for a 4 W transmitter. If it is more powerful, then “100” on the PA1 scale is set differently: by selecting a resistor that shunts PA1 with resistor R5 shorted.)
By switching SA1 to another position (reflected wave control), adjusting C2 achieves zero readings of PA1.
Then the input and output of the SWR meter are swapped (the SWR meter is symmetrical) and this procedure is repeated, setting C1 to the “zero” position.
This completes the adjustment of the SWR meter; its output is connected to the seventh turn of the L1 coil.
The SWR of the antenna path is determined by the formula: SWR = (A1+A2)/(A1-A2), where A1 is the readings of PA1 in the forward wave measurement mode, and A2 is the reverse wave. Although it would be more accurate to talk here not about SWR as such, but about the magnitude and nature of the antenna impedance reduced to the station’s antenna connector, about its difference from the active Ra = 50 Ohm.
The antenna path will be adjusted if by changing the length of the vibrator, counterweights, sometimes the length of the feeder, the inductance of the extension coil (if any), etc. the minimum possible SWR is obtained.
Some inaccuracy in antenna tuning can be compensated for by detuning the L1C7C8 circuit. This can be done with capacitor C7 or by changing the inductance of the circuit - for example, by introducing a small carbonyl core into L1.
To match the transceiver with various antennas, you can successfully use a simple hand-held tuner, the diagram of which is shown in the figure. It covers the frequency range from 1.8 to 29 MHz. In addition, this tuner can work as a simple antenna switch, which also has an equivalent load. The power supplied to the tuner depends on the gap between the plates of the variable capacitor C1 used - the larger it is, the better. With a gap of 1.5-2 mm, the tuner could withstand power up to 200 W (maybe more - my TRX did not have enough power for further experiments). You can turn on one of the SWR meters at the tuner input to measure SWR, although this is not necessary when the tuner is working together with imported transceivers - they all have a built-in SWR measurement function (SVR). Two (or more) RF connectors of the PL259 type allow you to connect the antenna selected using the S2 “Antenna Switch” slide switch for operation with the transceiver. The same switch has an “Equivalent” position, in which the transceiver can be connected to an equivalent load with a resistance of 50 Ohms. Using relay switching, you can enable the Bypass mode and the antenna or equivalent (depending on the position of the S2 antenna switch) will be directly connected to the transceiver.
As C1 and C2, standard KPE-2 with an air dielectric of 2x495 pF from industrial household receivers are used. Their sections are threaded through one plate. C1 involves two sections connected in parallel. It is mounted on a 5 mm thick plexiglass plate. In C2 – one section is involved. S1 – biscuits HF switch with 6 positions (2N6P biscuits made of ceramics, their contacts are connected in parallel). S2 - the same, but in three positions (2Н3П, or more positions depending on the number of antenna connectors). Coil L2 - wound with bare copper wire d=1 mm (preferably silver-plated), a total of 31 turns, winding with a small pitch, outer diameter 18 mm, bends from 9 + 9 + 9 + 4 turns. Coil L1 is the same, but 10 turns. The coils are installed mutually perpendicular. L2 can be soldered with leads to the contacts of the biscuit switch by bending the coil into a half ring. The tuner is installed using short thick (d=1.5-2 mm) pieces of bare copper wire. Relay type TKE52PD from the radio station R-130M. Naturally, the best option is to use higher frequency relays, for example, the REN33 type. The voltage for powering the relay is obtained from a simple rectifier assembled on a TVK-110L2 transformer and a KTs402 (KTs405) diode bridge or the like. The relay is switched by toggle switch S3 “Bypass” type MT-1, installed on the front panel of the tuner. Lamp La (optional) serves as a power-on indicator. It may turn out that in the low frequency ranges there is not enough capacity C2. Then, in parallel with C2, using relay P3 and toggle switch S4, you can connect either its second section or additional capacitors (select 50 - 120 pF - shown in the dotted line in the diagram).
According to the recommendation, the KPI axes are connected to the control handles through sections of durite gas hose, which serve as insulators. To fix them, water clamps d=6 mm were used. The tuner was made in a housing from the Elektronika-Kontur-80 kit. The somewhat larger housing dimensions than the tuner described in leave sufficient scope for improvements and modifications of this circuit. For example, a low-pass filter at the input, a 1:4 matching balun transformer at the output, a built-in SWR meter and others. For the tuner to operate effectively, do not forget about its good grounding.
A simple tuner for tuning a balanced line
The figure shows a diagram of a simple tuner for matching a symmetrical line. An LED is used as a setting indicator.
Today, on Sunday, I was visiting. Not far away, in a village almost the same as mine. And I saw how much more difficult it is to be a radio amateur without the help of more experienced comrades. I'm not talking about myself. Somewhat immodestly, but my contribution to the proposed material is mainly the translation from English. Because everything I offer has been known for a long time and has been published more than once in our Radio magazines. The emphasis this time will be on the word “simple”. Without abstruse shortening factors and words like “impedance”. And I will give the winding data of the coils. I really want to help those who have never had to take a course in radio engineering at an institute or technical school. After some thought, I decided to simply find a proven design.
Of course, I’m talking about “active” radio amateurs, those who try to make radio communications despite the lack of opportunity to use good antennas. Often a radio amateur gets a place of residence with limited space around. The “long wire” antenna, being the simplest, requires space (well, since it’s “long”) But it happens that even a half-wave LW does not fit in length. Sometimes it is only a few meters from the balcony to the nearest tree. Then antennas made of wire of random length are used. The lack of any matching reduces the 40 watts from the UW3DI to zero. At the same time, it is known that even a very shortened antenna can be made to work. And everyone knows the magic word for this - “matching”, and most radio amateurs perceive it this way - as a matcher of resistances, or rather impedances: - (and I promised not to say this word).
Note: About the antennas themselves. There are several tips that can improve the situation. Random-wire is not complete freedom, but a forced measure, so some points should still be taken into account. It is clear that if the antenna turns out to be shortened, then it needs to be stretched in the direction where its maximum length is possible. Twists and turns are undesirable, but not critical. Until the antenna wire goes in the opposite direction. There is no point in such an additional segment. The height of the suspension should be as high as possible. If it is possible to raise the horizontal part of the antenna up, then this should be done immediately when the conductor “exits” outside. And then stretch it to cover all the available space. It is better to make a “passage” through a window or wall through a porcelain (or RF insulator) tube. The wire itself must be of a minimum diameter so that it is as light as possible, but can withstand its weight. In addition, the thin wire is almost invisible. This can be a plus in terms of good relations with neighbors.
The proposed design (or two, if you count the SWR meter) is a random resistance transformer of a random length of wire into the required 50 or 75 ohms, depending on the design of the transmitter. Having suspended the “rope” in accordance with one’s capabilities in a position in which its length is maximum and its height from the ground is at the limit of what is possible, we obtain a problem with many unknowns. Or rather, with one unknown, depending on many others: the conductivity of the earth, the distance to the nearest physical objects, the change in the height of the suspension along the length of the antenna, etc. You can never say exactly what impedance and reactance the lower end of the wire will have. This is the main reason for the mistakes of not very experienced radio operators. They try to guess the resistance, use a transformer on ferrites or “binoculars” and bring everything to the feeder resistance. Meanwhile, the main thing is not to use a feeder and make the antenna part of the tuned circuit. Its impedance still remains an unknown quantity. But there is a way, using the method of successive approximations (scientific poking :-), to get closer to the effective use of what we have. In the case when we connect an antenna (any) to a transceiver with an autotuner via a cable, the tuner is tuned to the characteristic impedance of the cable and the antenna that follows it, like the next car on a train. If the cable length is predetermined as a wave follower, then the tuner will precisely tune the transmitter output to the antenna impedance. But it is not a fact that he will “see” the required antenna resistance. And if it is also unknown what it is, then there will be no result. 
The difference between this and what will be described below is precisely that in our case we will actually “introduce” the antenna and part of our device into resonance, achieving maximum antenna radiation, and at the same time achieving equality of transmitter-antenna resistances (conditions for which allows the maximum possible amount of energy to reach the antenna). Unfortunately, no one has repealed the laws of physics, and to use this (each specific) random length of wire at different ranges of the tuning interval of a variable capacitor (and the tapping point of the coil) will not be enough. Therefore, Lewis G. McCoy's W1ICP design, described in the book "ARRL Antenna Anthology", uses a system of a basic design with plug-in external inductor combinations to transform "everything into everything".
The photo shows the assembled device - with a built-in reflectometer and two sets of inductances on the connector. As you can see, the most important element is the “crocodiles” on flexible conductors. :-) You should immediately warn about taking the necessary precautions - there may be high voltage at the “hot” end of the circuit. Do not switch while the transmitter is on. This is dangerous primarily for the output stage transistors. Well, take care of your fingers - HF burns are guaranteed if these recommendations are not followed.
P.S. One of the side (and very unpleasant) effects will be a much closer location of the radiating element to your body, electronic devices, which it will, of course, interfere with, as well as the possibility of interference with the preliminary stages of your radio. For example, a significant improvement in protection against RF interference of the microphone (or ACC input when operating RTTY/PSK/SSTV) will be required.
And on the right are equivalent switching circuits for various LW options. Option A is best used when the antenna wire length is commensurate with the wavelength, options B and C for greatly shortened antennas. Such a flexible circuit and switching reversal allows you to effectively power any length in the range from 80 to 10 meters. Notice the word "feed". This is not the equivalent of the word "radiate". Although this is still the best way to use LW antennas that are not multiples of half-wavelength. 
Here is an even simpler equivalent circuit of an idea that I successfully used immediately after the army, without yet having a radio engineering education. All information was gleaned from the popular book “Radio is very simple” :-) Then my radio consisted of an R-250 and the legendary army transmitter RSB-5. The antenna, of course, is a long wire of unknown length from the window to the tree on the other side of the road. According to the above source, the resistance of a parallel oscillatory circuit varies from 0 at the ground point to an unknown, but maximum at the top point. By selecting the antenna connection point, you can find the best conditions - equality of the resistance of the antenna and part of the circuit :-), and the second connection point is the lower one - connecting the transmitter. And the task is made easier by the fact that its output impedance is known - 50 ohms. Therefore, it will be located significantly lower along the body of the circuit coil :-) Now I know that this is called an autotransformer :-) 
But be that as it may, if the household still has a variometer and a variable capacitor from RSB-5 (and the capacitor is good because it has a switch on the axis, which, when rotated by more than 180 degrees, connects a constant capacitance parallel to the plates), using two flexible conductors (gutted braid from any cable) and thin-lipped "crocodiles", then this can be used as a highly efficient autotransformer. Or rather, two autotransformers. 
But if there is a desire to repeat the design one to one, according to the author, then I continue. Here is a drawing (diagram) of the main structure. Its basis is a built-in SWR meter and a panel with a contact strip (one female connector, three male connectors) with five contacts. At this point I would deviate from the design and use ceramic biscuit switches like those found in the UW3DI or similar. From the point of view of ease of use (and preservation of the shape of the coils:-) it is incomparably better. As I mentioned above, when using one or two ranges, you can abandon this node altogether. And if you have a fairly reliable SWR meter, then you don’t have to use a built-in one either. But nevertheless, according to the author, everything looks like this:
In option A, a pure transformer with inductive coupling operates, and its value cannot be changed, which is not very good for a system that is tunable over a wide range of inductance and capacitance values. The adjustment is carried out by cyclic actions: connecting the antenna, tuning the C1L1 circuit to resonance at the maximum of the field strength “indicator” (“neonka” or field indicator), then adjusting the input C2 to the minimum SWR. Then reconnect the “crocodile” antenna conductor to another place and again adjust the settings and compare the results. Having achieved the best result, you can fix the connection point to the coil with paint, a drawing on a piece of paper :-) or write down the turn numbers. It may seem inconvenient, but after two or three settings, changing the range will be quick.
In options B and C, the connection with the oscillatory circuit, part of which is our wire of unknown length, is an autotransformer. Switching is carried out by connecting other strips with inductors and jumpers. Below are the circuits of options B and C. As you can see, in circuits with inductors, a variable capacitor moves from one end of the inductor to the other. 
In options B and C we see that these are options for our autotransformer with different transformation ratios (from the point of view of resistance, option C is option A on the contrary). Capacitor C1 with a maximum capacity of 150 to 300 pF. Coils L3 and L4 are the inductances of the couplers in the SWR meter and therefore are not considered separately. The data for coils L1 and L2 is below in the figure and in the text (since they are different for different ranges). For the range of 80 and 40 meters, they are made by frameless bifilar winding on insulating spacers with a wire with a diameter of 1.5 mm (#14 in the American style :-) with a pitch of 3 mm (8 turns per inch (25 mm) and a diameter of 65 mm. Every turn the wire is "pressed" inside the coil to secure the turns and make it easier to connect the "crocodile" to them. The coils have 18 and 6 turns, respectively, with one turn passing between them - instead of one turn, only half of it is laid (see figure and photo). This is quite labor-intensive part of the work, but it must be done very carefully, carefully pulling the wire and fixing the turns. 
For the ranges from 10 to 18 MHz, coils L1 and L2 are frameless with a diameter of 65 mm. L1 contains 4 turns with a winding length of 36 mm (in increments of 9 mm). L2 - one turn with the same pitch. It is located at a distance of 13 mm from L1. In the 21 to 28 MHz ranges, L1 has two turns, and L2 also has one turn of the same diameter and at the same distance from L1.
Of course, it is not necessary to repeat everything one to one; you can use either part of what was described, or even make the transmash a non-tunable lower part of the conductor of a single-band antenna, using an external SWR meter. But when setting up, you must also use a field strength indicator. Even the simplest one - a neon lamp or a fluorescent lamp. That is, the secret is simple: using two tuning tools you can get both a resonant antenna and the best SWR for an antenna in the form of a wire of random length. It seems to me that this is a very effective way to improve the quality of communication during field days, expeditions, and even in everyday work with radio.
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In everyday life, the concept is associated more with problems than with joys. Our hobby sometimes reveals unexpected facets that add positive emotions. Here's an example of SDR. My attitude towards them has already manifested itself more than once in the form of skeptical notes and even caricatures. For those who haven’t read it, visit my site more often and read longer :-) But the technology is developing and so many positive aspects have quietly accumulated that they began to balance my uncertainly good attitude towards SDR technologies.The first thing that really irritated me about SDR was one control: the mouse. Gray. With two buttons. By chance, at the request of Zhenya's neighbor US5UM, while adapting a double valcoder (Hercules) to his Flex3000, I noticed that now there are not enough hands :-) And two local oscillators can be turned simultaneously and the band can be changed with slide controls and switches as many times as you want..... In a word, mine skepticism has floated away....... But, continuing to persist, my brain absolutely does not accept the signal delay in the receiving and transmitting paths :-) DX already finished the call a second ago, and my SDR has just finished “chewing” the signal appointment. At this time, the smart guys had already given the call twice.... Working in a telegraph office without self-control is sad. When you turn on real control, the second or WEB receiver is simply terrifying! To the point that it is impossible to transfer.... Being late is simply confusing...
Quad-filament antenna for satellites
We are already tired of reading about all sorts of smart antenna settings. But the result still does not satisfy our inquisitive mind, either the polarization is not the same, or the diagram, or the amplification is either small or not at all. Isn’t there one antenna that is magical for a satellite, so that there is gain, and so that the polarization is circular, and so that the directivity doesn’t matter, the main thing is up :-) That is, the upper half of an isotropic antenna...?
There is such an antenna. And you most likely saw it. And more than once. If not in life, then on the Internet for sure. And it is called quadrifilar (they also add helix, in the sense of the Sun).
Vegetable garden field 2
I know for certain about two attempts to implement an antenna model code-named garden-field (out of modesty, my call sign is already famous :-) I personally have not seen a single implementation in practice. And I think I know the reason: plastic fishing rods with thin ends (with a span of 11 meters) will make anyone doubt the strength and durability of the structure. But numerous experiments with various antennas, including non-linear lengths of vibrators curved at different angles (Spider vs Hexabim ) and the latest variation of counterweights for a 160-meter antenna convinced me that the main thing in an antenna is still the length of the elements, and not their shape (location). As far as my mind was concerned, offhand, I drew the first drawing with shortened supporting structures (fishing rods) and asked Sergei UR5RMD, who is friends with MMANA, to check, or rather accurately calculate the elements of such a mechanically amplified antenna. I must say, the result confirmed my thoughts that from the point of view of electricity and radio engineering, little has changed. But from the point of view of the strength of the structure and its stability in the wind, the changes are radical.
Non-obvious
We, Ukrainians, are a special nation in general:-(We call blatant lack of culture a mentality. Militant ignorance is always presented as a principled position. And, as a special merit, the ability to color one’s own interests in the interests of the national flag, in public ones is respected. It’s sad, but we are okay with this , it seems, they still have a long time to live. Ukrainians don’t want to take off their rose-colored glasses and put on just glasses that improve their vision. I’m talking about the situation in the country in general and in Ukrainian amateur radio in particular. Unfortunately. That’s why Gogol wrote in Russia, and Sikorsky built a helicopter in America . People don’t want to hear others, see what is not obvious and look for other ways other than repeating yesterday. However, not only Ukrainians live blindfolded. Well, that’s just me, by the way. Because the movement of history (development) cannot be stopped and more and more more often people begin to see the non-obvious. When common sense, knowledge and intelligence begin to work, many familiar things begin to look different. How much can be changed for the better by stepping through the blinders of the so-called mentality. Or traditions, as you wish. Here, for example, is what a radio with an MP3 player looks like today.
As we have already written, the next step towards improving the quality of reception will be changing the power supply of the receivers themselves. Until now, they were all powered from the computer's USB port. It is clear that the purpose of these ports is not to serve as a source of high-quality supply voltage for SDR receivers that are very sensitive to voltage quality. This is the first thing. And secondly, to turn on two, three or more whistles, it is advisable not to load the port, but to use an external power source. The external source must be built according to the principle described and connected with a shielded wire in the section of the +5 volt power wire from the computer to devices connected to USB. To do this, the wire is cut, or rather, the plastic sheath and shielding foil are opened, to which the negative wire from the power source is immediately soldered. And the red wire is cut, the side that comes from the computer is muffled (isolated), and the positive wire from an external power source is connected to the wire going to the load. It looks something like this:
