Homemade kvsv meters. Ksw meter on strip lines
After completing the assembly of any antenna or antenna system, it is necessary to check the SWR. This will give you confidence that everything you have done has been done correctly. This SWR meter is designed to operate in the frequency ranges of 144, 432 and 1296 MHz.
Design
The design of the device is quite simple and understandable. The device is made of double-sided foil fiberglass with a thickness of 1.5...2.0 mm.
Figure 1 shows the installation of the SWR meter. The central conductor is made of brass rod with a diameter of 10 mm. The communication line is made from the output of the diode D1 and D2, since your diode will be practically inserted into the hole you made in the jumper.
All connections of the SWR meter body must be carefully soldered - this will ensure the rigidity of the structure and stability of the parameters. The partition installed between the measuring and instrument compartments of the SWR meter is shown in Fig. 2.
To decouple the measuring circuits, capacitors C3 and C4 must be support capacitors, for example, KDO brand and have a capacity of 3300 or 6800 pF. Other diodes can be used as diodes D1 and D2, but they ensure the operation of the SWR meter at these frequencies. Before installing diodes in the SWR meter, you need to check the passport data of the diode being installed.
The correct execution of the measuring compartment of the SWR meter in which the measuring lines are located is shown in Fig. 3.
Measurement
The measurement process has no special features, and has been described many times in various amateur radio literature. To make the calculation easier, Table 1 has been compiled. All values given in Table 1 were calculated for a 100 µA device.
Del......SWR
If you have another device that differs from the one offered, then you need to recalculate using the formula:
SWR = (Udirect + Uref) / (Udirect - Uref), where:
Upright - forward wave voltage
Uneg. - reflected wave voltage
After this, you can create a table, but for your device.
Modernization
To improve the parameters of your device, you need to modify resistors R1, R2, as well as capacitors C1, C2 using a solvent and remove the paint from them.
The lead going to the housing of the resistor R1, R2, as well as the lead of the capacitors C1, C2, must be minimally short and have soldering on both sides of the foil fiberglass, that is, the leads must be inserted into the hole you have previously prepared, the lead from the radio components must come out from the back side of the foil fiberglass by 1...2 mm and only after that soldering is carried out. Resistors R1 and R2 can be used as support stands and soldered vertically into foil fiberglass.
If you have a 100 µA device, which is recommended, then this design can be supplemented with another compartment by installing it in the SWR meter. If you assembled the installation correctly and maintained the dimensions, the SWR meter starts working immediately and all you have to do is calibrate it, i.e. create a table with SWR or plot these values on the scale of your device.
The dimensions of the compartment with the connector and the diameter of the brass tube are designed for a characteristic impedance of 75 ohms, and not 50. To achieve 50 ohms, you need to either increase the diameter of the brass rod by 5 millimeters, or reduce each side (as if the diameter) of the compartment with the “tube” by 11 millimeters ".
Remove the second capacitors from the diodes, unnecessary mismatch, leave one on each diode and shorten their leads as much as possible, primarily the leads of the capacitors that go to the diodes, but also to ground. Shorten the diode leads too. Use rigid, single-core wires to the toggle switch, with a minimum distance to the terminals. From the “common” output of the toggle switch, again solder a capacitance of several thousand pF to ground using the shortest route.
You can also solder the capacitance to the ground parallel to the connector. Try to place all elements as symmetrically as possible. In a compartment with connectors, it is advisable to solder the ground between the walls along the entire length. You should only look at the readings with the top cover closed.
I hope you installed 50 Ohm resistors, non-induction ones? Good thing, they need to be selected. And parallel to the multimeter probes, also place a small container on the multimeter itself, or even better, use the head, otherwise these Chinese multimeters...... And try to place the toggle switch vertically (i.e., rotate it 90 degrees, for "symmetry" :)
Diodes: GD501 507 508 D18 D28 D9 D2 D310 D311 It is advisable to select diodes according to the same current-voltage characteristic (volt-ampere characteristic) or similar parameters.
Calibrate the device using the nearest row of resistors: 50.75, 100,150 ohms (connected instead of the antenna), respectively, the SWR will be 1; 1.5; 2.0; 3.0. After this, you can check the device for symmetry (by swapping the input and output).
Do-it-yourself SWR meter (material suggested by Vladimir Neklyudov) Using a reflectometer, you can tune antennas, measure the output power of the transmitter, coordinate intermediate and output stages with each other, match the transmitter output at 144 MHz with the tripler input at 430 MHz and the tripler output with the load, etc. d. The schematic diagram of the reflectometer for the VHF bands 144/430 MHz is shown in Fig. 1. The basis of the device is a bidirectional coupler made on a strip line E1 with two communication loops L1 and L2. The voltages of the direct and reflected waves are removed from them, which are rectified by diodes V1 and V2. Depending on the position of switch S1, either one or the other voltage is measured. The communication loops are loaded by resistor R2. Resistor R1 adjusts the sensitivity of the device. The capacity of blocking capacitors C1 and C2 for the 144 MHz range is 0.022 μF, for 430 MHz - 220 pF. The design of the line with communication loops for the 144/430 MHz ranges is shown in Fig. 2a, b, respectively. Dimensions are given for an asymmetrical feeder with a characteristic impedance of 75 Ohms. The communication line and loops are made on printed circuit boards made of double-sided foil fiberglass 4 mm thick. When using another material, the line width can be found from the formula: where Z is the characteristic impedance of the line, Ohm; E - dielectric constant of the material used (for fiberglass E = 5); D - material thickness, mm; b - strip line width, mm. Printed circuit boards are soldered into a rectangular frame made of brass strip 0.8...1 mm thick and 30 mm wide. The printed circuit board must be soldered on both sides. Coaxial RF connectors can be mounted on the end walls of the frame. If you use the reflectometer in a specific circuit and do not intend to turn it off, the coaxial cable can be soldered directly. The input and output of the strip line are brought out through feed-through capacitors or pistons to the opposite side of the printed circuit board. Resistor R2, diodes and capacitors are placed on it. To do this, support points are made symmetrically to the terminals of the communication loops on the opposite side - annular grooves are cut out in the foil so as to create “spots” with a diameter of 5 mm. Diodes V1 and V2 and resistor R2 are soldered to these “spots”. Diodes are installed between the terminals of the communication loops and the blocking capacitors. Capacitors are used like KM, KGL or, in extreme cases, SGM. Their thin wire leads are cut off, and the diodes are soldered to the metallized section of the capacitor. The second plate of the capacitor is soldered to the common surface of the foil, as shown in Fig. 3. Soldering time should be minimal, since diodes will fail if overheated. Switch S1 - MT-1. Resistor R2 is non-inductive (ULI or MLT-0.25). The microammeter needle deflects by 100 μA to the full scale in the “Direct” switch position at a power of approximately 50 mW at 144 MHz and 100 mW at 430 MHz. At higher power, the sensitivity of the device must be reduced by introducing resistor R1. After installation and assembly, the reflectometer must be configured. To do this, a signal from the transmitter or GSS is supplied to the input, and the output is loaded with an equivalent load of 75 Ohms. You can use a ready-made HF equivalent from frequency response meters X1-13, X1-19, X1-30. Apply such an HF voltage so that the instrument needle deviates the full scale to the position of switch S1 “Direct”. Then the switch is switched to the “Reflected” position and by selecting resistor R2, a zero reading is achieved. This procedure is repeated several times with each of the newly switched on resistors. The adjusted reflectometer is closed on both sides with lids. Since reflectometers are symmetrical, their inputs and outputs can be swapped.
Almost all users of both “stationary” radio stations (including those intended for radio exchange on the civilian frequency of 27 MHz) and AM and 4M automobile transceivers (amplitude and frequency modulation) are faced with the need for optimal coordination of the antenna-feeder device (hereinafter referred to as the AFU) with transmitter. To increase the coverage area of a portable (wearable) radio, sometimes it is also connected to a corresponding external antenna. For example, in the CB range an antenna called “5/8” with vertical polarization and a pin of about 1450 mm is used. That is, solving this problem is important for all radio amateurs , conducting active and effective (over long distances) radio exchange.
Basically, external antennas of transceivers and radio stations (balcony, roof, car with various mounts) must be coordinated with the radio station transmitter so that at a certain frequency (for example, 27.0 MHz) there are minimal losses in the AFU. Almost all radio amateurs know about this. If this is not done, the useful power of the transmitter will be used ineffectively, that is, it will be difficult to achieve the maximum range of the radio station. A standing wave ratio meter (hereinafter referred to as SWR) is used for matching. However, you should not rush to buy this device in specialized stores - there it costs from 600 rubles. Those who rarely repair and configure radio stations use the services of “field specialists” to configure and coordinate transceivers and AFUs, which today is also very expensive, like any work in the field of maintenance and repair, although specialists still use the same SWR meters. Isn't it easier to assemble it for your needs yourself? For those radio amateurs who are ready to assemble an SWR meter themselves and learn how to use it, I suggest using the following recommendations.
To obtain the greatest efficiency of the CB radio station transmitter, it is necessary to provide an active resistance of the output of the transmitting node equal to the value of the characteristic impedance of the cable (feeder), and it, in turn, must correspond to the value of the resistance of the emitter (antenna pin, if we consider a simple antenna design).
Matching of the feeder and the pin is carried out by an inductor and a capacitor (tuning capacitor), installed, as a rule, at the base of the antenna. To do this, you will need to assemble a matching device with an SWR meter, the diagram of which is shown in Figure 1.
The matching device consists of two variable capacitors C1 and C2 with an air dielectric, for example KPE-4...50.1KLMV-1 and a frameless inductor L1. It contains 8 turns of 2.2 mm copper wire without insulation with a winding diameter of 25 mm and a length 22 mm. The inductance of such a coil will be 1.2 μH. The matching is adjusted using capacitors C1 and C2. The values are taken using an SWR meter, which shows how close the “radio station - feeder - antenna” system is to the traveling wave mode (no reflected signal from the load).
The matching device is connected to the transmitter antenna socket using a piece of cable (no more than a meter long) with a characteristic impedance of 50 Ohms, for example RK-50.
The SWR meter is structurally made from a section of the same cable of the RK-50 type, 160 mm long, with the external insulation removed. This section of cable, after all the preparatory work, is bent into a horseshoe. The wire screen is connected to the ground of the transmitter. The appearance of the finalized cable segment is shown in Figure 2.
1 - cable with removed external insulation (RK-50, L1000), 2 - internal cable core; 3 - insulated wire type MGTF-0.8; 4 - germanium diodes VD1, -VD2 (from the D2, D9, D220, D330 series)
The internal core of the cable is connected, respectively, at one end to the matching device (capacitor C2), and at the other to the antenna feeder. Inside the shielding wire of the SWR meter (a piece of cable 160 mm long with the insulation removed), a flexible insulated wire of type MGTF-0 is carefully laid using a needle, 8 and from its middle a tap is made to connect resistor R1. The ends of the internal wire MGTF-0.8 (any similar wire MGTF-1, MGTF-2 can be used) are soldered to germanium diodes VD1, VD2.
Fixed capacitors - tube Resistor R1 - with a dissipation power of 2 W, for example MLT-2 Its resistance can be in the range of 30 - 150 Ohms Fixed resistor 143 - type MLT-0.5. Variable resistor 142 - type SPO-1. Germanium diodes from the D2, D9, D220, D311 series with any letter index are used as diodes VD1, VD2.
Measuring device - any graduated one, with a total deviation current of 1 mA. Switch SB1 - toggle switch type, for example MTS-1
Any suitable, shielded housing for the SWR meter can be selected. The finished device looks (for example, like in the author’s version) as shown in the splash screen. Before turning on the radio station and the matching device, carry out the necessary preparatory work; connect the antenna-feeder device, set the SB1 switch to the “PR” position (to the left according to the diagram), and the AC motor resistor R2 - to the middle position. Next, matching is performed and the SWR is determined.
After supplying power to the radio station and turning it on in the “transmit” mode, by moving the slider of the variable resistor R2, achieve the maximum deviation of the milliammeter needle to the right, for example, to the number “10” (if this number is the maximum graduated value on the scale) After this, switch SB1 to the position “OBR” and record a new reading on the instrument scale (noticeably less than the previous one), which corresponds to the value of the backward wave.
Using the formula SWR = (Ppr+Result)/(Ppr-Response) find the value of SWR Ppr - the instrument reading in the forward wave recording mode (switch SB1 is in the left position according to the diagram) Restor - the instrument reading with a backward wave For example, Ppr = 10, Pobr = 2, then SWR = (10+2)/(10-2) = 12/8 = 1.5.
Wave reflection losses in the “transmitter - feeder - antenna” circuit depend on the SWR value and can be determined from the table below.
For optimal matching, it is advisable to set the SWR within 1.7 - 2; in this case, the wave reflection loss will be 5 - 12%, which is quite acceptable.
Provided that the length of the antenna pin is constant, by changing the capacitance of capacitors C1 and C2 of the matching device, as well as by changing the capacitance of the tuning capacitor at the base of the antenna, the required SWR values are achieved. If the antenna pin (and in some models its “counterweight”) is structurally capable of adjusting the length, then this is an additional lever for tuning the entire matching system. This simple method can be used to configure amateur radio transceivers of the CB range, car radios operating in the civilian frequency range of 27 MHz, with an output power of 2-15 W and equipped with antennas of simple design.
A. KASHKAROV
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SWR meters, widely known from amateur radio literature, are made using directional couplers and consist of a single-layer coil or ferrite ring core with several turns of wire. These devices have a number of disadvantages, the main one of which is that when measuring high powers, high-frequency “interference” appears in the measuring circuit, which requires additional costs and efforts to shield the detector part of the SWR meter to reduce the measurement error, and with the formal attitude of the radio amateur to the manufacture device, the SWR meter can cause a change in the wave impedance of the feeder line depending on the frequency.
The proposed SWR meter based on strip directional couplers is devoid of such disadvantages, is structurally designed as a separate independent device and allows you to determine the ratio of direct and reflected waves in the antenna circuit with an input power of up to 200 W in the frequency range 1 ... 50 MHz at the characteristic impedance of the feed line 50 Ohm.
The SWR meter circuit is simple:
If you only need to have an indicator of the transmitter output power or monitor the antenna current, you can use the following device:
When measuring SWR in lines with a characteristic impedance other than 50 Ohms, the values of resistors R1 and R2 should be changed to the value of the characteristic impedance of the line being measured.
Design
The SWR meter is made on a board made of double-sided fluoroplastic foil 2 mm thick. As a replacement, it is possible to use double-sided fiberglass.
Line L2 is made on the back side of the board and is shown as a broken line. Its dimensions are 11x70 mm. Pistons are inserted into the holes in line L2 for connectors XS1 and XS2, which are flared and soldered together with L2. The common bus on both sides of the board has the same configuration and is shaded on the board diagram. Holes are drilled in the corners of the board into which pieces of wire with a diameter of 2 mm are inserted, soldered on both sides of the common bus.
Lines L1 and L3 are located on the front side of the board and have dimensions: a straight section of 2x20 mm, the distance between them is 4 mm and are located symmetrically to the longitudinal axis of line L2. The displacement between them along the longitudinal axis L2 is 10 mm. All radio elements are located on the side of the strip lines L1 and L2 and are soldered overlapping directly to the printed conductors of the SWR meter board. The printed circuit board conductors should be silver plated.
The assembled board is soldered directly to the contacts of connectors XS1 and XS2. The use of additional connecting conductors or coaxial cable is prohibited.
The finished SWR meter is placed in a box made of non-magnetic material 3...4 mm thick. The common bus of the SWR meter board, the device body and connectors are electrically connected to each other.
The SWR reading is carried out as follows: in position S1 “Forward”, using R3, set the microammeter needle to the maximum value (100 µA) and by turning S1 to “Reverse”, the SWR value is counted. In this case, the device reading of 0 µA corresponds to SWR 1; 10 µA - SWR 1.22; 20 µA - SWR 1.5; 30 µA - SWR 1.85; 40 µA - SWR 2.33; 50 µA - SWR 3; 60 µA - SWR 4; 70 µA - SWR 5.67; 80 µA - 9; 90 µA - SWR 19.
These can antennas are mostly praised. So I decided to check what real range they have and what SWR they have. I will start with a whip antenna, as the simplest and most effective, tested by experience in long-distance communications. This design can be useful for all occasions or on all sides of radiation and reception, since in the horizontal plane it has a circular radiation pattern.
The graph shows the dependence of SWR (standing wave ratio) on frequency in the range from 100 to 2000 MHz.
The optimal SWR value is one, this is the dip in the frequency response, the frequency range that provides the best matching. Changing the SWR value from 1 (excellent) to 2 (quite satisfactory). The size of each horizontal cell corresponds to 200 MHz. With a large swath, the instrument error is maximum.
Whip antenna design.
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| Photo 1. |
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| Photo 2. |
I only needed two half-liter containers, where one can serves as an emitter, and the second as a counterweight. The purpose of the counterweight is to reduce high-frequency currents along the outer braid of the coaxial cable and ensure better coordination with it. For convenience, I used high-frequency connectors (thus obtaining a dismountable antenna), although the braid of the coaxial cable and the central wire can be secured with nuts, washers and screws. The place where the wires and connectors were attached to the jar was cleaned of varnish or cling film for better contact. I punched a hole in the bottom of one can and passed a coaxial cable with a characteristic impedance of 50 Ohms. On the opposite side of the can, I secured the cable braid, and connected its central conductor to the other can.
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| Photo 3. |
Thus, the upper bank is a quarter-wave emitter, and the lower one, which I called a counterweight, lives up to its name as a balancing device. Thanks to this design, I can examine the antenna via a connecting cable at some distance from the generator in order to evaluate its parameters separately from the device, and not in conjunction with it.
Characteristics of a whip antenna.
Input impedance 50 Ohm. Range 240 – 830 MHz. SWR within 1.0 – 2.0.
Circular radiation pattern in the horizontal plane.
I measured the antenna using several instruments, not forgetting to use a homemade SWR meter. Thus, my SWR meter received certification, since the characteristics of the antennas under study coincided.
I can now say with confidence that the result is a fairly broadband antenna that covers the range from 240 MHz to 830 MHz. Thus, the antenna is tuned to all analog television channels of the UHF range, including all multiplex packages of terrestrial digital television, amateur radio bands 70 cm (430 - 438 MHz) and the PMR communication range (446 MHz). In the operating frequency range it The SWR ranges from 1.0 to 2.0. Good performance, at least the transmitter will give maximum power to the airwaves, since its output stage is perfectly matched to the homemade design.
To receive television programs, you should use horizontal polarization by placing the jars horizontally and turning them in this plane to find the optimal reception level.
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| Photo 4. Factory design whip antenna. |
Using beer cans to make antennas is not know-how. Similar antennas have long been used in mass production and at the same time have good characteristics. Outwardly, they look like pins, but they have the ability to work with coaxial cable, therefore they have better efficiency due to their higher location from the surface of the earth.
In photo 4, the antenna is made of hollow brass cylinders.
Antenna designGroundPlane".
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The next type of antenna, no less effective and widespread, is the vertical antenna with “Ground Plane” counterweights. The only difference is that the counterweights, their number usually ranges from 3 to 4 (it was convenient for me to make 4) and they are located at an angle from 40 to 90 degrees to the vertical. More time was spent on its production, although all that was required was to cut the counterweight jar and spread the petals at an angle to the vertical. The design turned out to be very clumsy, which cannot be said about the characteristics. The SWR is practically the same as that of a whip antenna and the matching range is slightly larger.
Antenna characteristics «GroundPlane".
Input impedance 50 Ohm. Range from 220 to 900 MHz. SWR within 1.2 to 2.2.
Design of a symmetrical split vibrator.
I couldn’t pass by the split vibrator, also made from two containers. Such an antenna is also called a horizontal half-wave dipole. These are the antennas that most DIY enthusiasts use. Its input impedance is 73 -75 Ohms, and the radiation pattern is significantly different from previous antennas. This is a figure eight with two maxima of radiation and reception in the horizontal plane of the dipole and with a minimum of radiation and reception at the ends. Of course, I was a little confused by the lack of a balun, but it didn’t stop me from checking the real SWR values in the frequency range in the form of these antennas as they are used in practice.
The matching range is quite wide and ranges from 190 MHz to 770 MHz, as you can see it has shifted down a little. SWR values are slightly worse compared to a whip antenna. In the frequency range, some SWR values are slightly higher than 2.2, that is, by a minus three. Perhaps with a U-elb type matching device, with an oscillator with an output impedance of 75 Ohms rather than 50 Ohms, the SWR will improve, but the range will narrow.
Characteristics of a symmetrical split vibrator.
Input impedance 75 Ohm. Range 180 – 750 MHz. SWR ranges from 1.0 to 2.2.
Conclusions. There are still benefits from beer. At least it leaves behind empty containers, from which you can actually make an antenna with good characteristics. According to theory, the operating bandwidth should be within 30 percent of the center frequency, but in practice it turned out to be larger.
All of the antennas listed above have virtually no gain, since they do not have a pronounced one-way radiation pattern. This drawback can be easily corrected by giving the antenna directional properties by installing behind it a metal screen in the form of a rectangle with sides no less than 1.5 times the overall size of the connected cansor a metal mesh with a pitch of no more than 1 cm. In practice, the distance from the screen to the cans is slightly less than the 4th part of the wavelength and is found experimentally by increasing the signal level at the antenna output, which increases to 5 dB and significantly increases the reception or transmission range.
SWR, characteristics, and will the antenna work? This weekend I decided to test the first version of the whip antenna outside the city at the maximum distance from it, which is about 90 kilometers. The testing location is already known to many - it is an attic, and the antenna itself is not outdoor, but indoor, which indicates the worst test conditions for it. When you connect the antenna via a 2-meter cable (50 Ohm) to the TV, programs are broadcast in the decimeter wavelength range with interference in the form of snow. I put a reflector in the shape of a jam bowl, which was used in the manufacture of the detector receiver, and the snow on the TV screen noticeably weakens. I connect a set-top box to receive terrestrial digital television, and three multiplex digital packages are transmitted in 100 percent quality with a signal level of 30 percent. I change the basin to a barbecue grill, and the quality is lost by 20 percent.
Thus, the antenna works like an indoor antenna and works without an amplifier.
There are still many containers of different calibers ahead. If you hate to pour out the beer, use aluminum foil. For further independent work, I propose to make a simple homemade SWR meter.
Homemade SWR meter.
Modern instruments for measuring antenna characteristics are very complex and prohibitively expensive. However, having a wide-range high-frequency generator and a simple homemade SWR meter, you can determine the antenna matching in the frequency band used or adjust the antenna to the desired receiving or transmitting frequency based on the SWR value. The minimum SWR value in most cases indicates the resonant frequency of the antenna.
A homemade SWR meter is a bridge type device. With the same resistance of a resistive load of 50 Ohms and an antenna with a similar resistance, currents of the same magnitude on the millivoltmeter will be subtracted, and the reading of the device will be equal to 0, and SWR = 1. If the resistance of the antenna differs from the resistance of the load of 50 Ohms in one direction or another, then the currents will have different values, and the SWR will deteriorate.
In practice, values of SWR = 1 are considered excellent, and SWR = 2 are considered satisfactory.
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| Photo 7. |
The board with high-frequency connectors must be placed directly in the housing, to the place where the antenna under test will be connected. For some types of whip antennas, the housing will act as a counterweight. If the product body is plastic, then the printed circuit board itself is used as a counterweight, in which the antenna connector is installed.
Calibration From the generator I apply the level to the full deflection of the microammeter needle V p, in my case this conventional value is V p = 200 (divisions of the entire microammeter scale). I connect a 50 Ohm resistor to the antenna connector and the device shows V and = 0.
SWR = (V p + V u) / (V p – V u) = 1; SWR = (200 + 0) / (200 – 0) = 1
Measurement. Now, instead of a resistor, I connect an antenna and use the same formula to calculate the SWR. At each measurement point I check the radiation efficiency of the antenna itself. To do this, I bring a sheet of metal commensurate with its size to the antenna being measured, waving it like a fan. At some distance (this will depend on the power of the generator and the directional properties of the antenna, so the distance is from 10 cm to 1 meter), the antenna will begin to receive the field reflected from the sheet, and its characteristics will change in time with the oscillation of the “fan”, and the milliammeter needle will begin to deviate in one direction or another. The longer the antenna's breathing distance, the more effective it is. Using this method, you can practically imagine the radiation pattern of the antenna, that is, in which direction it radiates most effectively.
If a device for studying frequency characteristics (X1 - 42, X1 - 50, X 1 - 51, etc.) is supplemented with a homemade SWR meter, then you can observe the change in SWR by frequency on the screen. I connect the wire going to the microammeter to the UPT input of the curve tracer (where the detector head is usually connected), and on the curve tracer I set the maximum output and visibility, then the antenna resonance is a dip in the frequency response, which will correspond to the SWR tending to unity. The unity SWR level is also calibrated by connecting a 50 ohm resistive load in place of the antenna.
Oh, and don't forget to wave your fan.
