DIY antenna for a radio in a car and its setup. Antenna for a walkie-talkie with your own hands Homemade antenna for a pmr walkie-talkie

You can install a walkie-talkie in your car for various reasons. This could be a future car trip with friends on vacation, or even a passion for eavesdropping on other people's conversations in a car. But basically such a device is installed either by taxi drivers or truckers. Whatever the reason, a walkie-talkie antenna must be installed for the unit to operate properly.

This installation may seem simple only at first glance. In fact, there are several nuances that need to be taken into account when choosing, manufacturing and installing an antenna.

Types of external transceiver devices

There are two types of antennas for radios in a car:

• mortise:
• with magnetic base.

They are not fundamentally different. The main difference is that a built-in antenna for a walkie-talkie is stationary, while one with a magnetic base is removable; it can be removed or moved to another location.

Built-in antennas

From the name it is clear that they are attached in one place. Therefore, before installing this device, you need to carefully think about where to install it so that it doesn’t interfere and the reception is good. You should also take into account the fact: the antenna for the radio in the car must be attached to the supporting body. If you neglect this postulate and install it, for example, on the hood or wing, that is, on a false mass, the efficiency of the device is lost by 30-40%. Some car enthusiasts are trying to improve this system and try to connect the mass with additional wires to the body. But still the desired effect cannot be achieved in this way. Although sometimes it works, it is extremely rare. As a rule, such an antenna for a walkie-talkie still works quite well for reception, but transmission using such a device is very bad.

Height will be an important factor when installing. The higher the device is installed, the more efficient its operation will be. For example, if you install an antenna in a car bumper, the transmission and reception range is reduced by half.

It is optimal to install the antenna in the middle of the roof. Some craftsmen convince that it can be installed with equal success on a bracket in the corner of the roof. But there are some points that need to be taken into account for expedient installation. If installing a radio is needed only for driving around the city, then the mounting option on a bracket is completely suitable. This will not affect the operation of the device due to the fact that a directional effect will not be created in the city due to additional reflections. If this device is installed for long trips along the highway, then installing an antenna for car radios in the corner of the roof will be impractical.

Installation of a mortise antenna

When installing the antenna in the roof, it is necessary to reinforce the joint with an additional metal plate. This is necessary primarily for greater connection strength.

The canvas itself and the extension coil should be as far as possible from all vertical metal planes that are located parallel to the base of the antenna. The minimum distance between them should be 50 cm. If this factor is neglected, the device will not work properly due to the high reactivity of the space. This nuance should be taken into account when installing antennas for car radios, including trucks.

Antennas with magnetic base

An antenna with a magnetic base, or, as it is popularly called, “magnetic”, can be used on any car. But there are several points that should be observed when installing it.

1. For more efficient work And correct settings This device should also be installed on a supporting body.
2. Under no circumstances should you change the length of the cable from the antenna. This will make it impossible to configure or will degrade the performance of the device.
3. It is not recommended to roll the cable into a coil; this can also adversely affect the operation of the device. If the cable is longer than necessary, then you just need to carefully lay it around the cabin.
4. The position of the antenna on the roof can be arbitrary. This type is not too demanding on location. But if there is a need to dismantle the device, then the next time you have to use it again, you should try to put the antenna in the same place.

DIY radio antenna

The most simple option The solution to this type of car upgrade would be to purchase an antenna. But it can also be made independently. To do this, you can follow the step-by-step instructions.

1. Take a simple antenna-whip from a radio. All it needs is a foundation.
2. Buy metal knitting needles with a diameter of 3-4 mm.
3. Make an extension coil. It should be on a 10 mm mandrel. For it to work properly, you need to wind 44 turns of PEV 0.41 wire.
4. Next, you should solder the ends of the coil to the brass bushings. This will ensure good contact and will create additional structural strength.
5. After this, you need to connect the spokes to the bushings at each end. It is important that both knitting needles are the same length.
6. Next, the SWR meter is adjusted and the spokes and coil are adjusted.
7. Then the antenna for car radios is directly installed.
8. Open the ceiling.
9. Unscrew the standard antenna, unscrew 2 screws, remove the active amplifier board and carefully unsolder it.
10. Solder a 50 ohm coaxial cable into place. It is important to maintain the order of the veins, mass to mass.
11. All connections should be sealed.
12. Route the coaxial wire under the trim and rug and lead it to the radio.
13. Attach the antenna in place.

If all steps of the algorithm were completed correctly, then the antenna for the walkie-talkie is made with your own hands. You can proceed to the next stage - configuration. But, according to experts, this is a rather complex and delicate process. This is due to many aspects: you need to be able to solder carefully, winding the coil is also not easy to do correctly. As a conclusion: a homemade device can only be made by a sufficiently trained amateur. Otherwise, you won’t get a good antenna for a walkie-talkie this way.

Antenna setup

If the antenna is installed correctly and correctly, then it only needs minor adjustments. But many car enthusiasts approach this process skeptically, thinking that this element of the communication system is not particularly important for the operation of the entire device. And they are deeply mistaken. Not only the reception signal, but also the operation of the device itself depends on how correctly the antenna for the radio is installed and the device is configured. Moreover, if you configure the radio incorrectly, you can damage not only the transistors of the output stage, but also ruin the device itself.

Step-by-step setup instructions

The radio antenna should be configured according to the following algorithm:

• For correct settings, you must have a device such as an SWR meter.
• The setup process must be done away from structures made of metal, concrete or wood. It is advisable that trees be placed no closer than 15-20 m.
• It is highly advisable to stop the car on a clean, level and dry surface.
• Antenna tuning may also be affected by nearby vehicles with radio antennas. Next, you need to install the SWR meter according to the instructions, that is, between the radio itself and the antenna. In this case, you cannot use an amplifier.
• Measurements with the device must be made on several different channels and at different points. It is advisable to carry out this procedure in different grids. This will allow you to see the real picture of the settings.
• The next step is very important: you should find the minimum SWR indicator, ideally the indicator should be equal to 1, it is advisable to write down where it is located. If it is located at a frequency below the specified one, this means that the antenna needs to be shortened. Accordingly, if it is higher, you need to lengthen it.
• The next step is to shorten or lengthen the antenna, depending on the SWR readings of the device. Lengthening or shortening is the process of adding or, conversely, unwinding turns from the matching coil, and not shortening the antenna with wire cutters.
• After this, you again need to look at the SWR meter. Repeat the procedure until the desired result is achieved. Sometimes in some models it is not possible to achieve the ideal indicator, but this is not a big deal. If the indicator deviates, for example to 1.5, the losses will be equal to 5%. The walkie-talkie will work quite normally even with an indicator of 3. If an amplifier is built into the system, you need to take into account that the minimum indicator should not exceed 2.

If all steps of the algorithm are completed correctly, the antenna for the radio in the car will serve perfectly.

Avoid making antennas for radios for cars with your own hands for the simple reason that the equipment is difficult to set up later. Standard devices at the base contain a nut-like unit that allows the driver to adjust the device to the wave being used. For manual models the situation is different. An antenna for a walkie-talkie can be made with your own hands, but problems will arise for large enterprises purchasing frequencies. The state committee monitors the goods sold so that consumers avoid mutual interference. Railways do not intersect with shipyards. Sometimes industrialists need communications, everyone will start improving the equipment, we will find a situation: subscribers will hear each other. Working at different companies. Ask SCRF: they will give recommendations; perhaps it will be enough to demonstrate the modification in action to specialists to assess the impact on neighboring communication domains.

Communications and radio antennas

They have repeatedly said: in everyday life, linear and circular polarization are more often used, the latter mainly on satellites. Walkie-talkies are no exception. Horizontal polarization was taken away by television, leaving vertical polarization to radio broadcasting... walkie-talkies. Logical. When we hold the radio, the antenna is positioned vertically. The signal reflected by the terrain is visible, rotated at a fixed angle. Thanks to the effect, the dull military man demonstrates a “violation” of the laws of physics... Ideal reception is carried out by a vertically standing antenna. If you don't believe me, do the opposite!

Those who read reviews about homemade antennas will be amazed, but not surprised. Again, single-ended quarter-wave vibrators made from a piece of standard coaxial cable. Polarization, frequencies, why something has to change. Once they said: TV antenna You can place the cable vertically, catch the radio, if you find one on the desired wavelength...

Original radio antenna. Inside the knob there is a copper spiral, the tip of which is attached in the area of ​​the top. With some walkie-talkies you can simply get to the curls, with others the problem is unsolvable. Why spiral?

According to the course of electrodynamics of radio wave propagation, the antenna radiates in the direction of the axis, the wave will be polarized in a circle, according to the direction of the curl. Only if the coil length is close to the wavelength. The context in question assumes a figure of half a meter or more, forget about proximity.

The MMANA program gives an idea of ​​the radiation pattern. Well-wishers kindly put a radio antenna there (145 MHz), avoiding changing the parameters, looked at the field (opening the application):

1. In vertical polarization, an even circle emerged in azimuth. It is clear that the human body will distort the diagram! Indeed, the spiral emits vertical polarization almost exactly. The level is – 3 dBi.
2. The horizontal polarization shape resembles a figure eight, the level is much lower. If you hold the radio with a spiral antenna horizontally, the reception will deteriorate and will not reach zero.

At the angle of elevation with horizontal polarization a semicircle is formed, with vertical polarization a dip is formed along the axis. No useful upward signal is emitted. Let the man with the walkie-talkie climb the tree. And both hold the devices vertically, the reception will be due only to the horizontal component, as well as the reflected signal. These are the antennas that walkie-talkies use... It is not surprising that amateurs are tempted to change the design. Therefore, spirals are used.

In reality - and on the MMA file - the antenna consists of a spiral, the cap plays a significant role. The idea is clear. In real conditions, communication must be carried out in all directions; a quarter-wave vibrator is unable to meet the specified requirements. Why a quarter? The half-wave vibrator is longer. Dimensions matter. The spirals began to twist not from a full life. It's just that a long antenna for a walkie-talkie is too much of a luxury. It will pierce your pocket, you will be tortured to hold it with your hand, and windy weather will make you vomit. You have to make sacrifices. Let us recall that in terms of vertical polarization, the radiation pattern demonstrates the similarity of a torus, typically. The horizontal one adds something like a dumbbell (rough approximation), forming the missing corners and areas of space. The radiation pattern for reception and transmission is the same.

We will design walkie-talkies by removing unusual reception properties in all directions. The energy will rush towards the torus. The broadcast range will increase. If we re-equip both radios, we will get an additional gain at the cost of losing the final reception (transmission) from above and below. We remind you that the radiation patterns for reception and transmission are the same (identical).

Let's increase the range of the radio station by modifying the antenna

The conclusion is obvious: we want to increase the range - we saw the radiation pattern of the factory antenna - we need to direct the power to vertical polarization, to the torus. How to do it is clear, but one question looms on the horizon - the wave impedance of the radio antenna. Do you know the meaning? They talked about how to try it on! If the length of the feed line is a multiple of half the wavelength, the antenna impedance is transmitted to the output without change. We use the effect for measurement.

Various devices are used (HF generator). For those thinking about taking one, let’s say: the TV’s local oscillator is capable of producing a similar frequency, but setting it up is another matter. Let's talk separately. You will need a high-frequency voltmeter; a conventional one is unsuitable for measurement purposes. The device is measured by the voltage of the RF generator in a suspended state, the scale is calibrated to show 100%. Assemble a circuit connected in series:

• antennas;
• variable resistor.

Connect the generator to the circuit and measure the voltage of the resistor. Turn the adjustment until the arrow starts to show 50%. The resistance of the variable resistor becomes equal to the characteristic impedance of the antenna. It is necessary to take a non-inductive reactance (which does not have its own inductance). A homemade radio antenna should, if possible, repeat electrical parameters factory. The characteristic impedance is taken to be close to the original one. The measurement process is clear to readers.

The designer's choice is small: two global families. Cables with characteristic impedance 50, 75 Ohm. The first is used by communications, the second by television. The antenna of a portable radio is made from the one that is closer in nominal value to the measured value. The quarter-wave vibrator (without a spiral) has a resistance of 35 Ohms. It is difficult to predict the parameters of a purchased antenna. It is easier for practitioners to make two antennas for a walkie-talkie using different types of cable. Then test each one on the ground, assessing the nature of the changes.

Making a radio antenna

Let us briefly recall the process of manufacturing an antenna for a walkie-talkie. Considered digital television, WiFi, 3G. The audience of the VashTekhnik portal knows how to make an antenna for a walkie-talkie. Feel free to copy the methods. First you need to know the frequency. More precisely - better. The radios have several channels, the frequencies are registered in the passport. Select a channel by specifying the antenna dimensions.

Let the frequency be 435 MHz. We find the wavelength using the school formula, dividing the speed of light by the indicated value: 299792458 / 435000000 = 689 mm. To make a quarter-wave vibrator, you need to divide the number by another 4, we get - 172.25. The length of the antenna for the walkie-talkie will be 17 cm. Try to keep the millimeters more accurately. The screen does not need to be cleaned. It will be a receiving surface, the band will increase. If your hands are itchy, peel off the braid and leave the dielectric around the main core.

The old antenna is desoldered, a clamp is ready for the new one. All that remains is to fix it in place, enjoy the connection. The antenna for the walkie-talkie is made by hand. By the way, if you don’t want to remove the screen, solder it together with the core in one bundle when mounting it on the chip. If you consider expanding the range unnecessary, it’s better to remove the screen. The first and second options have advantages; the solid cable is stronger. It's better to leave it as is. The radio antenna will last longer. Make sure to glue on a nice cap-tip so that the copper stops oxidizing. We say goodbye until next time.

Copy factory designs. Enterprise radios break down. The adapters remain, the devices are thrown away. An invaluable chance for a radio amateur to prove himself. The antenna is covered with rubber, which can be easily peeled off. Or use an accessory from a broken product. The process of copying is not directly prohibited, except for products protected by patents. The case concerns the industrial production of products for the purpose of marketing, obtaining a fixed profit by performing the specified actions.

Having experimented with the communication range depending on the terrain and having made a number of conclusions for myself, I focused on working in a network of Internet relays LPDnet.

It is also worth mentioning the first experience of working through a crossband. One afternoon I unsuccessfully called Kolya RN3KK on 433.500 (before that, calls were made at a pre-agreed time) and Sergei RN3KU answered me. At that time, he had a Yaesu FT-8800R and could easily listen to two frequencies at once. Word for word and he suggested that I make a crossband 433.500<-->145.500 so that I can call RN3KK there. There were already real radio amateurs there, of whom you still see quite rarely on 433 to this day. In general, having called RN3KK on 145.500 several times, I did not hear him, but other radio amateurs answered. After telling me who I am, where I’m from and what I work from, they told me that Kolya RN3KK hasn’t been here (145.500) on FM for a very long time, but works in SSB on 144.300. Communication with Kolya RN3KK failed that day, but I met Sergei RN3KU, who later crossbanded me several times to the frequency of the local Echolink. For which I thank him very much!

It was possible to work in LPDnet without problems only from the balcony, because... there were the best indicators for reception/transmission. Climbing around the site LPDnet, I found many descriptions on the manufacture of antennas, but one caught my attention - the Kharchenko antenna.

And it attracted me, first of all, because of its ease of manufacture (it is made from one piece of wire), has a pronounced directivity (when using a reflector) and a good gain (8-10 dB).

There were no particular problems in the manufacture of the antenna itself, except that there was nothing to make a reflector from. The antenna sheet was first made from copper wire with a cross-section of 1.5 mm 2 , but later began to be made from wire with a cross-section of 2-2.5 mm 2 because it is more rigid and does not bend under light loads. Also, the thickness of the vibrator material affects the broadband.

I hung the antenna on the balcony window, since it looks strictly in the direction of one of the LPD links. Among other things, the window plays the role of a rotating device - by opening and closing it, you can change the direction for reception/transmission. Perhaps the power supply to the antenna is not supplied correctly - in Kharchenko’s works and in the figure above, the feeder is supplied along one of the “arms” of the antenna, but in mine from below and immediately to the center. Distortion of the radiation pattern and large SWR values ​​are quite likely, but more on that later.

At that time, my main problem was connecting this antenna to the radio station. The cable is simply soldered to the antenna, but it is attached to the radio station via an SMA connector (in my case). I described how to solve this issue in an article entitled “ Method for crimping an RG-8X cable with an SMA connector for an RG-58 cable " As a result, my connection looked like this:

In general, the reception/transmission situation has changed dramatically for the better - I sometimes accepted the link up to 9++, and opened it with 0.5W. Before installing this antenna, I had not heard Andrey RL3QAM, when he, being at the threshold of the building where the link was installed, was broadcasting from his portable laptop with an elastic band. That day I was able to talk to him on the direct channel with 100% intelligibility. However, problems arose with soldering the cable to the antenna sheet - over time, the contact came off. This was solved by better re-soldering and careful fastening of the cable to the window frame, so as not to create a load when opening/closing the window. There was also a problem at the junction of the RG-8X cable with the RG-58 - the transition from a thick cable to a thin one. Sometimes there was a bad contact, and if the SMA connector was frequently unscrewed/screwed on, the contact in the connector itself deteriorated, until the cable disconnected from the connector at the moment of unscrewing. All this negatively affected reception/transmission.

The solution came in the form of an SMA (male)-BNC (female) adapter. The problem was to get it at that time, but now it’s on Ali.

A piece of RG-58 is bitten off and thrown away. The remaining cable is stripped and crimped with a BNC connector (Ali has straight or angled ones).

There are different BNC connectors - for different cables, with different types fastenings (crimping, soldering, screw), straight and angular. Crimp the cable with a connector screw fastening does not leave much difficulty, but in any case, soldering will always be more reliable and better. But for experiments this will do.

Straight connectors are crimped in the same way:

As a result, everything looks much more beautiful and reliable:

After using such an adapter, the problems with poor contact where the cable was attached to the station connector disappeared. Various other adapters also exist, such as SMA-PL.

The main problem with them is their availability in stores and their prices. The original ones from Yaesu are an order of magnitude more expensive than these unnamed ones.

The next problem that had to be solved was power problem. It consisted in the fact that my portables were powered by rechargeable batteries. Batteries tend to discharge, and charging the batteries requires time during which the radio must be turned off. The time was 10-14 hours. Those. During this time I was unable to receive or transmit anything. Having noticed on the VX-177 the label for the charging connector as “EXT DC”, which meant “external power”, I thought about this very external power, or rather about the source. The original charger was only suitable for charging the battery, although in reception mode the station could also work from charging, but they wrote on the Internet that charging should not be used for other purposes. Someone tried it and the chargers died. And then, listening is one thing, but transmitting and listening is another. On the Midlands 500, operation from anything other than batteries was not provided, except that charging was possible not through the glass, but through the microphone connector. They wrote about this, but that's another story.

After talking on this topic with Kolya RN3KK and Andrey RL3QAM, I came to the conclusion that the simplest power source is a converted power supply from a computer. I just had one like this without need. After a visit to RN3KK, I had a disassembled power supply with a large number of bitten wires, a jumper to turn on the power supply and marked places for soldering. Having soldered + and –, I started experimenting.

I decided to connect to the station not through the charging connector, but directly to the battery terminals. I just didn't have a suitable plug at hand. To do this, I first determined where the + and where – are on the battery, and then connected the power using “crocodiles”.

The station turned on and showed a voltage of 12V. Well, sometimes 11.9V.

Everything would be fine, but when receiving signals from the speaker, in addition to the speech of the correspondents, some kind of buzzing and buzzing could be heard and made intelligibility very difficult. In addition, the power supply itself made a crackling noise.

On the advice of Andrey RL3QAM, since he had experience in remaking computer power supplies to power his links, two capacitors and one ROLL stabilizer were purchased (I don’t remember the markings, but it’s not visible in the photo...).

After a visit to Andrey RL3QAM, I had a power supply with soldered-in air conditioners to filter out interference from the power supply itself and a stabilizer to reduce the output voltage to 9V (just in case). This radically corrected the situation - the buzzing and crackling in the station dynamics disappeared, but the crackling in the power supply itself did not disappear. In any case, thanks to Andrey for your help!

I did not power the VX-177 with this power supply for very long, because... Somewhat later, the option of using another computer power supply appeared, but in any case, using a power supply is much more convenient than using batteries that need to be charged. And later, somewhere I got hold of an ancient computer power supply unit, which, after modification, which consisted of soldering a jumper, installing a power switch, biting out all unnecessary wires and soldering wires of the required length to + and - 12V, worked completely silently (only the fan was spinning) and gave 10-11V. Also, subsequently I used the connection of the station through the corresponding connector using a plug. For this power supply unit we should thank Kolya RN3KK, to whom the old power supply unit was given for experiments. Later Kolya reported that the crackling power supply was like a time bomb.

But the experiments with nutrition did not end there. Somehow I came across a pair of used lead-acid batteries from a UPS. The batteries were CSB GP 1272 with a capacity of 7.2 Ah, with a voltage of 12V. The idea to try such a battery as a power source came at a time when the power was turned off for a long time. Yes, there is a native one accumulator battery, but with intensive use it will fail faster, and a new one costs much more than CSB GP 1272 or similar. So, why not, if you are at home, but without electricity (temporarily), use such a battery? In general, the experiment was successful - the station was powered by such a battery without any problems, and at 5W of power everything worked fine, there was no significant voltage drop. True, the batteries were already worn out, and they were enough for 30 minutes of transmission. I purchased a couple of these new batteries and Charger from 220V for them. Later these batteries were very useful to me, but at that time it looked like this:

The downside was that the battery could not be discharged below 10.8V, otherwise the lead plates would already be destroyed. To know current voltage you had to either look at the built-in voltmeter of the VX-177 and not see any other information on the display, or, as was done, connect a separate voltmeter and always see the current voltage level. True, the battery in the multimeter had to be changed quite often.

To summarize, I’ll note the fact that, somehow, without noticing it, I tried to make a base station out of a laptop... and it worked. External antenna, power supply from 220V, PTT....

In most cases, when it comes to antennas, people think of large “dishes” that are installed outside a window or on the roof of a house. However, it is worth understanding that this is far from the case. The fact is that the size of the antenna depends on what frequency and wavelength it will catch. Naturally, if you want to catch a satellite signal in order to broadcast several dozen television channels, then you will need a large antenna. But you don’t always need such a signal. That is why it is worth considering such a thing as a 433 MHz antenna. This device is very different from the antennas you are used to seeing on windows and roofs. It is very small and, as can be seen from the name, does not receive the longest signal waves. Why might such waves be useful? Most people don't pay much attention to them, but if you like to fill your home with various remote-controlled items, then you'll definitely need more than one 433 MHz antenna. If you learn to use their properties, you will be able to create things in your apartment such as a radio socket or even a pet feeder with remote control. Interested? Then read the article below and you will find out what this antenna is, how to use it, where to buy it, and most importantly, how to make it with my own hands, if you don't want to spend money on a purchase.

What kind of antenna is this?

So, first of all, you need to understand what a 433 MHz antenna is. As you can already understand, this is a device that allows you to tune a certain device to a specific frequency in order to then interact with it. By installing an antenna in a specific device, you can then send a signal to it at a specific frequency to activate and control that device. This is very useful feature in any home, as you can significantly simplify many processes. However, not everyone can do something similar - you need to be well versed in this area in order to tune the devices to the desired frequency. But if you set a goal for yourself, you can definitely achieve it. You just have to try hard, and you should start by studying this particular antenna, since it is one of the most important elements. You should definitely know that the 433 MHz antenna comes in three types: whip, helical and etched. printed circuit board. How are they different? Which one is better to choose? This is exactly what will be discussed next. It's up to you to learn what each of these antennas are and figure out which one is best for your specific purpose.

Whip antennas

How can you get a 433 MHz antenna at your disposal? It’s quite easy to make it yourself, but you can also buy a ready-made one, which will cost you a little more, but will save you a little time. In any case, you first need to decide which type you want to get. And the first type we will talk about is a whip antenna. Its main advantage is that it has the best specifications compared to other types. That is why people almost always make a choice in its favor. Moreover, it is much easier to do it yourself. So overall it's best antenna at 433 MHz, made with your own hands or bought in a store. However, you shouldn’t think that she’s perfect. If this were the case, then there would simply be no need for other types. That is why it is necessary to separately consider the disadvantages that this type of antenna has so that you are aware of all the features before making a purchasing decision.

Disadvantages of whip antennas

The first disadvantage that 433 MHz whip directional antennas have is their susceptibility to environmental influences. The problem is the very strong reflection and interference that occurs if you try to use the antenna indoors. Thus, it is more suitable for portable devices rather than home appliances, since in homes, due to the small amount of space, obstacles such as furniture and walls, the signal may be distorted, lost and not reach the target device. So first of all, you should think about the purpose for which you are going to use the antenna, and then decide whether to buy it. However, this is not the only drawback of whip antennas, which initially might seem ideal. It turns out that the pin in this antenna must be almost (or completely) parallel to the ground plane on which the structure itself is located. As you can easily understand, this is very difficult to implement in small household appliances. Therefore, you may have already figured out that 433 MHz whip directional antennas are best suited for various portable devices of more or less large size or those on which the antenna can be installed externally. It is not recommended to use such antennas at home. But what should replace them then? As far as you remember, there are two more types of such antennas, so it’s time to pay attention to them.

Helix antennas

The easiest thing you will get is a homemade whip antenna at 433 MHz, however, as you may have noticed above, it is not ideal. Therefore, it is worth paying attention to other types, for example, a helical antenna. How is it different from a pin one? Firstly, it also has good technical characteristics, so in this regard you can use both the first and second types with complete peace of mind. What about interference? It turns out that they are also present in a spiral antenna in enclosed spaces, and sometimes they are even stronger than in whip antennas. Therefore, it remains to look at the last parameter - compactness. As you remember, whip antennas, due to their design, must either be placed on the device body or inside it, but at the same time there must be quite a lot of free space inside the device, which is difficult to achieve when it comes to small household appliances home use. And in this parameter, the helical antenna bypasses the whip antenna, because it is extremely compact and will allow you to make almost every device in your home radio-controlled. Naturally, a DIY 433MHz directional antenna made this way will take you much longer, but if you are looking to buy an antenna, then you should definitely look at the helix versions as they can come in handy and help you out a lot.

Antenna on board

If you need a high-quality compact collinear antenna at 433 MHz, then you should definitely pay attention to this type, that is, antennas that are embedded in the board. It means that this type It is impossible (or very difficult) to do it yourself, so they will be considered exclusively as purchased. What are their advantages over the two types described above? First of all, they have good characteristics. Of course, not as impressive as the previous two options, but good enough for everyday use. Their main advantage is their compactness - such antennas can be placed in absolutely any device. But, as mentioned above, their main drawback is that a do-it-yourself dual-band 144-433 MHz antenna on a board is something fantastic. That is why this option will not be considered further for the reason that the rest of the article will be devoted to creating an antenna with your own hands. How difficult is it to do? What will you need for this? You will learn about all this further.

Necessary calculations

But if you decide to make an antenna with your own hands, then you will need a lot of theoretical knowledge on this topic. The fact is that any deviation in the manufacturing process will not allow you to tune the antenna to receive a specific frequency. Therefore, everything must be done very accurately, so it is always recommended to start with calculations. Making them isn't that difficult because all you need to calculate is the wavelength. Perhaps you are good at physics, so it will be much easier for you, since you will understand what we are talking about. But even if physics isn't your strong suit, you don't necessarily need to understand what every variable means to make the necessary calculations. So, how is the length of a 433 MHz antenna calculated? The most basic equation you need to know is the one that will allow you to calculate the required antenna length. To do this you need first since the length of the antenna is one fourth of the wavelength. Those people who understand physics can themselves calculate the required wavelength for a specific frequency: in this case it is 433 MHz. What needs to be done? You need to take the speed of light, which is constant, and then divide it by the frequency you need. The result is that the wavelength for a given frequency is about 69 centimeters, but at this detailed settings It is better to use more precise values, so it is worth keeping at least two decimal places, that is, the final result is 69.14 centimeters. Now you need to divide the resulting value by four, and you get a quarter of the wavelength, that is, 17.3 centimeters. This is the length your 433 MHz J antenna should be, or whatever style you want to use. Remember that regardless of the type, the length of the antenna must remain the same.

Use of the received data

Now you need to put the data you have gained into practice. Antenna 144-433 MHz can be made different ways, however practical use theoretical information should always be the same. What is it about? First, you should always use a wire that is a few centimeters longer than the desired antenna length. Why? The fact is that in theory everything turns out quite accurately, but in practice everything will not always work as you plan. Therefore, you should always have some reserve in case something goes wrong or the signal is not picked up at the frequency you wanted. You can always easily bite the wire in a specific place once you determine the required length. Secondly, you should always remember that the length is measured from the place where the wire comes out of the base. Thus, the resulting 17 centimeters should be measured from the base of your antenna. Most often you will have to use slightly longer wire as you will need to solder your antenna. A 433 MHz whip antenna will work better the more pins you use, so you'll want to make sure each one is the same length.

Preparation of materials

So, the theory is over, it's time to get down to practice. And for this you will need to take everything you need to create your own antenna. First of all, these are the wire or rods that will make up the main receiving part of your antenna. Secondly, you will need a base for your antenna. It is advisable that it has several holes that you can use to attach pins. If these holes are missing, you will have to either drill holes or solder directly to straight metal, which is not very convenient and will not allow you to correctly calculate the length in advance. Therefore, use a base with pre-drilled holes. Naturally, you will need other things, such as a soldering iron, but everyone knows about this, so there is no point in listing all such items.

Execution of work

First of all, you need to prepare material for further work. To do this, you need to clean all the pins, tin them and treat them with flux. After this, you need to cut the pins to the required length, but do not forget to leave a little length so that you can then adjust the finished result. Then you need to get down to soldering - each of the pins needs to be soldered with reverse side antenna, and then take another one that will be attached to the antenna. Its length no longer plays a role, since it will serve as a holder and will not be responsible for receiving the signal. It also needs to be soldered, after which you can already admire the result of your work.

Final steps

Well, your antenna is now ready to use. All you have to do is take the final steps. Trim the excess length of the pins so that the signal is received perfectly. If you have heat shrink, use it. And remember - this is just one example of a homemade antenna. You can also make a helix antenna, but your design of a whip antenna may look completely different. However, calculations to obtain the length of the antenna are relevant in any case, and the steps to create an antenna with your own hands will also differ only in details.

Almost all LPD radio stations that are widely used in Lately are equipped with shortened antennas, the efficiency of which often leaves much to be desired. Some radio stations in this range are designed with the ability to work with another antenna (includes an antenna connector). The use of an external, more efficient antenna allows the operation of such radio stations to increase reception stability and radio communication range compared to operation with standard antennas. Below is a widely used design of such an antenna for the LPD and simple technology making it at home. The manufacture of this antenna does not require scarce materials, and if you have some skills in working with a soldering iron, this antenna module can be manufactured within half an hour.

Structurally, the antenna is a block connector with a flange (1) on which a quarter-wave pin (2) and four “counterweights” (3) are mounted. The designs of similar antennas encountered differ from each other in the type of connector used and the material used to make the pin and counterweights (usually either copper, which leads to low rigidity of the entire structure, or brass pins, which increases the weight of the structure and requires the use of powerful soldering irons when soldering). When developing this antenna, the priority was to reduce the weight of the structure and simplify its manufacturing technology.
What do we need to make?
Firstly, a block connector BNC socket with a flange for crimping an RG58 cable (see photo). You can, in principle, use a BNC connector with a threaded solder socket, but then you will have to make the flange yourself and fix it to the connector using a nut with a lock washer. The use of the BNC connector is driven by both the desire to reduce weight and the widespread availability of BNC cable connectors (in older computer networks on coaxial).
We calmly remove the crimp tube from the connector kit (we won’t need it).

The second “necessary component” for our design is five ordinary bicycle spokes, which can be easily purchased at any bicycle parts store. The bicycle spokes have a diameter of 2 mm, a good anti-corrosion coating and great rigidity, which is important for our “melted” design. We don't need the spoke nuts and can add them to the crimp tube from the connector.

First of all, we press out the flange at the connector so that it can be further warmed up painlessly during soldering. If you do not do this and warm up the entire connector, the internal insert of the connector, made of plastic, will melt (unlike the good old CP-50, where this insert was made of fluoroplastic).

Screw four spokes into the threaded holes of the connector flange

We form “counterweights” from the spokes by bending them 45 degrees relative to the axis of the flange.

Armed with a soldering iron, solder and acid flux, we solder the threaded connections.

After the flange has cooled, we wash it thoroughly, first with soap (to neutralize the remaining acid flux) then with alcohol (to degrease and remove residual rosin).
After washing, press the flange back onto the connector.

Let's put our “umbrella” aside for now and move on to the emitter pin. Here we need a connector insert and a fifth spoke.

We grind the end of the spoke so that it fits into the hole in the connector insert

Armed with a soldering iron and acid flux, we first tin the turned end of the knitting needle, and then solder the knitting needle into the insert.

We wash the soldering area with soap and water, then degrease it with alcohol. We take a piece of heat-shrinkable tubing, put it on the soldering area and heat it up.

Trim off excess thermophyte.

Insert the central pin into the connector.

We take another piece of heat-shrink tubing, put it on the connector so that it completely covers both the connector shank and the section of the knitting needle with thermofit and warm it up.

Trim off excess thermophyte. Our pin is fixed in the connector.

We “cut” the knitting needles in accordance with the dimensions in the drawing. (The linear dimensions of the central emitter pin and “counterweights” are measured from the extreme point of the connector tube in the area where the emitter pin exits.)
So we have received hardware with which we can already work.

If you plan to permanently place the antenna on the street, then you need to make a “couple of touches” - protect the ends of the spokes where the anti-corrosion coating is damaged. One way is to tin the ends of the knitting needles with acid flux and then wash them thoroughly (first with soap, then with alcohol).
The second protection option can be to cover the spokes with heat-shrinkable cambric. In this case, to prevent moisture from leaking into the connector, the cambric must be “dressed” over the entire pin from the end to the flange. We put a plastic “pipe” on the end of the pin, which prevents direct moisture from entering the end of the pin and additionally serves as protection against “eye disease” during operation.

As a result of the work done, we received an antenna module with low weight and very good rigidity, which is very important for the stability of the geometric characteristics of the antenna, and therefore its electrical characteristics.

To connect to the radio station, all we have to do is cut the cable. At one end of the cable we cut the pin-BNC connector, at the other - the connector for connecting to the LPD radio station (most likely this is a pin-SMA for stations such as Midland GXT-400, GXT-500, YAESU VX-5, VX-6, VX7 etc. or SMA socket for the JJ-Connect family of radios with antenna connector). At the second end of the cable, you can also separate the pin-BNC connector and connect the station via an adapter. For a short cable length (up to about 3-4 m), you can use the widely used RG58. At such lengths, losses in it can be neglected in favor of its flexibility. If you need a greater distance of the antenna from the radio station, then it is advisable to look for a cable with lower losses.

We cut the cable and connect it to our “umbrella”. The issue of mounting our antenna either on the radio itself, or on a car, or on a balcony is already a “different topic” that has many options and we will not consider it here