DIY auto antenna repair

In detail: do-it-yourself auto antenna repair from a real master for the site my.housecope.com.

Sooner or later, all things fail. Sometimes through the fault of the owner, and sometimes through the fault of the manufacturer's plant. But one way or another, in our time of permanent crises, sometimes there is simply no way to spend money on a new thing, especially since DIY repair is not so difficult. And in this article I will talk about a special case of repairing the Optim CB-2001 antenna.

In principle, I have already described this technology in an article about a fake Lemm AT-2001 Turbo, and if you haven’t read this article yet, I recommend reading it. After reading these two articles, you will know in detail how to repair a car communication antenna with your own hands.

This antenna, Optim CB-2001, was sent to me by Alexey from Novorossiysk with a request to repair and return it to the air. What I actually did.

The antenna was disassembled, a separate case, a separate top cover, there was no cone into which the pin was inserted, and the upper bronze bushing was torn from its rightful place and dangled on the upper terminal of the hot coil.

Apparently, this knot loosened and the bolt simply "gnawed" through the fiberglass insulator, falling off it.

And the first thing we need to do is secure it in place. For this we use a regular cyanoacrylate-based superglue.

We put the top sleeve in place, glue it with superglue and let it dry.

Obviously this will be extremely fragile, so the next step is to reinforce the hot coil with epoxy. However, before filling the antenna coil with epoxy, I strongly recommend that you clean all surfaces of the antenna and thoroughly solder the coil. I described how to do this in the article about preparing antennas for operation.

Video (click to play).

We get EDP glue in a hardware store, this, in fact, is the very same epoxy.

We take out the bottles from the box.

Pour one and a half parts of epoxy resin and one and a half parts of hardener into a suitable container. One part corresponds to the volume of liquid between the marks on the surface and the label of the vials.

As a vessel for mixing epoxy components, I chose an ordinary plastic cup. The volume of resin in the photo is taken with a margin, you can take less.

After adding the hardener, mix the epoxy resin thoroughly for 5 minutes.

Before pouring the epoxy into the coil, the joints should be lightly sealed to prevent the resin from leaking out of the coil. To do this, I simply applied a little flux gel for soldering to the joints. Also for these purposes you can use the well-known LITOL-24.

We put the coil vertically, clamp it in a vice, the outer case.

In order to securely fix the upper sleeve on the insulator, pour a little ready-made epoxy into the sleeve, being careful not to get into the threads. Do not fill the entire internal volume, since after the resin has hardened, you will not be able to screw the upper cone with the pin into the antenna.

After this procedure, carefully fill the inner volume of the coil with epoxy resin. Take your time and let's get air out.

You need to fill it up to about this volume.

The final stage, we cover everything with a top cover that will center the coil and leave it all for 24, or even better for 48 hours until the epoxy resin has completely solidified.

After that, of course, the hot coil becomes non-separable, but protected from any surprises and you can no longer worry about the safety of the antenna.

Car antennas today are diverging in purpose.In combat conditions they catch communications, in peaceful conditions - broadcast channels, navigation information. The car antenna is a quarter-wave vibrator supplemented with matching devices. Signal line, the body of the car will serve as the ground. Due to these two components, signal reception becomes possible. Due to the simplicity of the design, they make a car antenna with their own hands. First, determine the purpose of the device, the wavelength range, the type of modulation. Three main components of the design.

We mentioned the types of car antennas, we will give an excessive classification:

Purpose:

Reception of broadcasting.
Reception of TV broadcasting.
Reception of satellite information of navigation systems.
Connected car antennas.

Method of installing antennas on cars:

Magnetic.
On a suction cup.
Mortise.
Threaded connection.
On a clamp.
Embedded.

Wiring diagram for the car antenna under the rear wing

By location:

Outdoor car antennas.
Salon (internal).

Amplification type:

Active.
Passive.

Surely an experienced car enthusiast will be able to add a couple of signs, we restrict ourselves to the specified classification. FM antennas fit inside the passenger compartment. Amateurs make accessories with their own hands, using lengths of cable with a characteristic impedance of 50 ohms. The braid is electrically combined with the car body (mass). Beware of catching lightning while driving through the field. The thunderstorm chooses the point closest to the sky.

The size of the car antenna depends on the range. Messengers (radio frequency 27 MHz) of large size. Powerful varieties reach a length of 2 meters (put on trucks), according to science, they should be made 50 cm higher. To match the differences between the actual size, a quarter-wavelength "extension" coil at the base. For use, the installation of a car antenna for communication is carried out vertically. Due to the type of polarization. The communication antenna can be tilted by means of a lamb, a lever, so as not to break, driving through the forest, overcoming the spans of a low bridge. Most of the drivers of large trucks use the communication antennas. It is allowed to equip jeeps, civil cars, at times the view will turn out to be unsightly.

Note. Factory antennas are tuned to the wavelength. The mustache is shortened, equipped at the end with a protective cap. The operation is carried out according to the instructions. The manual includes a chart of recommended sizes. Violation causes a drop in reception sensitivity.

The digital car antenna for TV reception looks like a police flasher, made in a different color scheme. The device is devoid of unnecessary bells and whistles, accepts a frequency of hundreds of MHz. The first multiplex in Moscow was chosen by 559 MHz. The digital car antenna on a magnet is located at the top (roof), the wire runs over the door without modifications. Horizontal polarization signal, the task of the device is to receive an arbitrary azimuth.

Broadcast antennas rarely boast a large size, since the wavelength is higher, the dimensions are larger. Small height pins, like decorating portable radios. Beware of accidentally buying a car radio antenna designed by the manufacturers to decorate your TV receiver. Fearing to be mistaken, read the technical specifications in the store:

Radio is designated FM, AM (frequencies 70 - 108 MHz).
Television - DVB - T (frequencies below 900 MHz).
Navigation - GPS (about 400 MHz).
Radio communication - CB (27 MHz).

Sometimes dealers forget to indicate the capabilities of an antenna. The range is 400 - 530 MHz, it is mentioned, "the option of receiving GPS signals is available." One can only guess what the copy can do, the first Moscow multiplex passes by. Frequencies above 400 MHz are used by portable radios, departmental communications of the Ministry of Internal Affairs.

It remains to pay attention to the connector.It coincides with the vast majority of devices for which it is intended, it will not be out of place to verify the compatibility issue. They say that an external car antenna catches better, the question concerns mainly city reception. Rushing along the track, the windows of a typical passenger car will not create serious obstacles to the passage of electromagnetic radiation. Intra-salon car antennas are easier to install. Accessories are lower than the outer ones, hence the inferior quality.

The store will provide all sorts of hybrid models, including options a la All-in-One. You can switch the reception from city to road. Differs in sensitivity, interference suppression features. Out-of-town reception range increases, amounting to 80 km. They sell peculiar tandems. A pair of similar pins is laid out, one of which catches TV broadcasting, the other - radio, communication. The use of the charms of the set requires the purchase of appropriate receiving equipment.

The only difficulty: the body of the car is constantly moving. Traditional terrestrial domestic antennas in this case will form reception dead zones. There will be long periods of time when maneuvering when there is no reception. Refers to horizontal polarization, not vertical polarization! In the latter case, the antenna does not care about the azimuth of the signal arrival. The mast is upright! This was discussed by ordinary loop biquad antennas, quarter-wave vertical dipoles. Let's see what else is useful to nature.

Zeroing the braid by means of mass

How to make a car antenna with your own hands so that:

did not cause complaints from the traffic police for unnecessary revision of the body;
got up in the salon;
ensured reliable reception of radio frequencies;
had a high efficiency (since you need to work on transmission).

The quarter-wave vibrator suits the named case poorly. Difficult to manufacture, has a relatively large size (see above), difficult to attach, interferes with driving. Here is the notion of the drivers of VAZ 2106 cars (an experienced radio amateur will remake the concept, abstracting from the brand of the car).

A frame structure is used, which is laid under the car's rear window seal. Slightly narrowed upwards, slightly different sizes than required by a frequency of 27 MHz, a capacitor is located in the center, which tunes the car antenna into resonance on the desired channel. Please note that there are two receiving frequencies:

The upper resonance falls on the lower range of radio broadcasting. The car antenna circuit is simple:

It is necessary to lay out the perimeter of the rear window with a trapezoid with a MGTF 0.5 wire:

The upper edge is 56.5 + 56.5 cm.
The lower edge is 66.5 + 66.5 cm.
The sides are 22.5 + 22.5 and 45 cm.

Coiled section reduces overall antenna length

The pluses are, where we will add the wires of the matching capacitor, remove the signal with the cable RK - 50.
In the middle of the glass, two wires go vertically to the center, where a trimmer capacitor is attached exactly along the axis (5 - 25 pF). Each one is 45 cm long. Therefore, you will have to twist it in a zigzag, put it under the insulating tube.
We solder the cable from the side where the wire is cut in the middle. There should be no gap on the opposite side.

The car antenna is connected through the connector used by the communication equipment. The length of the cable is short, or rather, you should take a smaller one. Since the antenna is passive, the signal will be strongly attenuated in the path to the receiver. If you put really connected equipment at the rear window, it’s worth doing so.

See advantage. It is unlikely that our antenna for a car with your own hands will differ in too long a range, show miracles of reception, but it is competitive with some factory models mounted on the roof, they have a height greater than a passenger car. Plus in the forest, the city will not hurt. In addition, there is no need to wind the matching device.This is not easy, in addition to accurately maintaining the number, the pitch of the turns, it will be necessary to find the required wire thickness. The structure will have to be sealed; the event will require the purchase of a number of additional materials.

Will understand the meaning once holding a walkie-talkie with his hands. The antenna is covered with a dense sealant, the devices will allow broadcasting, at best, for a couple of kilometers. If the terrain is not rugged. In our case, ease of installation, ease of construction, and accessibility for the average user are achieved.

A capacitor is required: the circuit is shortened. According to the author of the idea, the coefficient is 0.3. The middle stubs are used to electrically lengthen the frame to the desired size, the capacitor extinguishes the reactance to match the RK-50 cable and will allow the system to be tuned into resonance. The author claims that the antenna is broadband. In most cases, it is possible to perform installation on the rear window of any car without major design changes. The setting is based on the minimum standing wave ratio.

In some cases, buying an antenna for a car and installing it will be more expensive, more difficult and provide a lower quality of reception. There is nothing difficult in the above design, and every motorist can try the accessory in his spare time. A two-meter mast will not fit a passenger car, more appropriate on a tank! Which, as you know, are not afraid of dirt.

No car audio system that includes a radio is complete without an antenna. There are different types of antennas (outdoor and indoor, active and passive).

We decided to install an in-car active antenna with attachment to the windshield on the car. Antenna of this type is characterized by ease of installation, does not require maintenance, does not wear out and does not create aerodynamic drag. Other advantages of such an antenna include the fact that it does not attract the attention of car thieves, since it is not easy to remove it from the car.

True, with all the positive qualities, it should be noted that its sensitivity changes depending on the orientation of the car relative to the radio station transmitter.
According to the installation method, such an antenna is disposable. On its body and poles ("whiskers") there is a sticky film, which secures the antenna elements to the windshield. Once these elements have been removed, it will no longer be possible to reattach them to the glass.

In addition to the antenna itself, the kit includes detailed installation instructions, as well as materials, fixtures and templates to facilitate installation and reduce labor and time costs.
There are two options for installing the housing and antenna "mustache" on the windshield. In the first case, the antenna body is installed in the middle, in the upper part of the glass (behind the rear-view mirror), and both antenna poles are glued on both sides of the mirror along the upper edge of the glass. In the second case, the antenna body is installed in the upper right corner of the windshield, and the "mustache" is glued along the upper and side edges of the glass.

The book describes the second option for installing the antenna.

SEQUENCING

Thoroughly clean the inner surface of the windshield from dirt ...

... and degrease it with a napkin soaked in a cleaning agent, and then wipe it with a dry napkin.

Now the glass surface is prepared for gluing the housing mounting plate and antenna poles.
To glue the plate, use the included thick paper template. The template has slots that allow the plate to be inserted into it in only one position.

We insert the pin and the plate latches into the slot of the template.

Remove the protective sticker from the smooth side of the plate and press the plate together with the template to the glass so that the two corners of the template touch the corresponding sides of the glass edge.

We remove the template from the plate.

In order for the antenna "mustache" to be glued to the glass equidistantly to its edges, the antenna installation kit includes a set of distance templates (pieces of white adhesive tape).

We glue the templates on the glass perpendicular to its edges.

Antenna pole is a piece of wire, on one side of which a contact tab is soldered. The wire and the contact tab are located on a transparent plastic tape with an adhesive layer. The adhesive layer is covered with a white protective film, which must be removed before gluing the "mustache". After removing the film, we put the contact eyelet on the pin of the housing mounting plate.

Gently glue the "mustache" to the glass along the edges of the spacers (for clarity, the protective film has not been removed).

After sticking the antenna "mustache", smooth them out with a special spatula included in the kit.
The right sun visor must be removed to route the antenna wires.

Pulling the roof lining towards us, we pass the grounding cable through the hole in the upholstery and pull it out.

Remove the front roof pillar lining.
We stretch the wires behind the roof upholstery and remove them from under the upholstery.
We install the antenna housing on the mounting plate.
When installing, the pin of the fastening plate, on which the antenna "mustache" contact ears are put, must go into the hole in the antenna body. When the case is properly connected to the plate, the characteristic clicks of the plastic latches should be heard.

To fix the antenna body on the mounting plate, screw in the screw.

The tightening torque should not be high, otherwise cracks may appear in the plastic parts.

We pass the antenna cable into the gap between the windshield frame and the instrument panel trim.

We stretch the cable into the glove box and pass it over the plastic bracket of the instrument panel.
After completing the cable laying, we ensure that there are no loops and sagging along its entire length. Make sure that the cable does not touch sharp edges of the body and is not overstretched.
Reinstall the front roof pillar lining.
Trying not to damage the conductors of the ground loop, we make a hole in the loop with an awl and, separating the conductors, we increase the diameter of the hole so much ...

... so that a self-tapping screw can pass through it.

We insert the self-tapping screw into the visor bracket and put the grounding cable on the self-tapping screw rod. Lubricate the contact part of the loop and the self-tapping screw with anti-corrosion grease, which is included in the antenna installation kit. We remove the excess length of the train under the roof upholstery.
Install the sun visor in place and tighten the screws.
We connect the antenna cable to the radio. The power supply wire of the antenna amplifier (red) is connected to the radio tape recorder wire to supply power to the automatic retractable antenna drive. In this case, power will be supplied to the amplifier only when the radio is turned on.

Car antennas have long been considered an everyday accessory, but this technique often breaks down, often it is simply stolen. Factory models are quite expensive, and it is often difficult to find a suitable one. However, you can make auto antennas for the radio with your own hands. The process is simple, but it requires some professional skills.

The range of devices in stores is very large. By purpose, this technique is divided into the following types:

Active antennas for a car radio, when the signal is received together with a built-in amplifier. They are considered to be very powerful. Great for long distance signal pickup.
Passive models. They work without amplifiers. They are considered simpler, it is much easier to make them yourself. Such devices are just recommended to be installed if car radios are used only in the vicinity of the city.

Antennas are also classified according to the method of installation. Distinguish between internal and external antennas:

Internal. They are installed in car interiors.This installation method is suitable for active models.
External. They are located outside the car bodies. This installation is more suitable for passive devices. At the same time, the low power of the equipment is somehow compensated.

To make an antenna for a car radio with your own hands, you need to take into account the principles of the signal catcher, determine the length of the device, its location, the degree of complexity of the entire structure.

Conventional antennas for cars are quarter-wave vibrators that are grounded to car bodies. Such devices can only be mounted vertically, and reach 2.5 m in length. For antennas of standard car radios, these parameters are considered redundant.

That is why, to replace obsolete oversized devices, they use independently made external antennas for car radios. To hear stable radio signals in the popular range, it is enough to use pin devices with a length of 10 to 20 cm.

In addition to significant cost savings, there are a number of other advantages to using this technique. The following advantages are distinguished:

The self-made design can be tailored to completely different car models.
There will be no problem with the installation height for receiving radio signals.
Installing a homemade device is much easier than factory counterparts.
It is possible to improve the quality of signal reception with the correct installation of the installation, as opposed to using commercial antennas.

It is worth noting that it is possible to start independent design if you have the skills to work with electrical engineering, otherwise it is better to use the services of professionals or use store counterparts.

You can make with your own hands both inactive and active (with an amplifier) devices. The production technology consists of several stages:

preparation of the necessary tools;
direct assembly;
attachments to the machine body;
connections.

Assembling different types of antennas for a radio tape recorder with your own hands differs significantly even in the selection of the necessary tools.Passive antennas without an amplifier are considered fairly simple in design. To create such a device, you will need:

copper wire (diameter from 1.5-2 mm);

high quality nut;

good file;

screwdriver;

thermal glue (can be replaced with a heat shrink tube);

screw (diameter M5);

lock-nut.

Take a copper wire, twist it to a length suitable for a particular car.

The resulting spiral is pushed onto an M5 screw, secured with a nut and locknut of the same size (soldered on top). The structure is treated with thermal glue, or wrapped using heat shrink tubing.

The surface is sanded with a file. This procedure is done under the condition that the spiral was treated with glue (only after the substance has completely dried).

Install a homemade antenna. The spiral blank is inserted into the hole made (at the base), the wires are connected.

To give an aesthetic appearance to the installation, a film is glued onto it, treated with a primer, and painted. The passive device is ready.

A feature of this technique is the presence of equipment that enhances the reception of signals. When creating internal active installations, frame structures are used. This requires the following tools:

copper wire, always with insulation (diameter - 2 mm);
home amplifier (a television device will do);
high quality soldering iron;
connector that is suitable for the radio;
good wire cutters;
glue.

An amplifier enclosure designed for a conventional home antenna is often used as the basic basis for a device. A wire is soldered to it, which, in turn, will be connected to the radio tape recorder. This is necessary in order for the amplifier to receive and transmit signals.

An antenna plug is connected to the socket, a connector is mounted on the other end of the wire. The power cable for the amplifier in car radios is considered a control cable, it is colored blue.

An active type receiver is mounted on the roof of the car so that signals are well received. To do this, two holes are drilled in the body - mounting and auxiliary. The antenna wire is laid along the perimeter of the driver's door, fixing it with glue. After installation on the roof of the car, fix the (side) cable in the rack, carefully connect it to the car radio.

Traditionally, active types of antennas for radio tape recorders are installed on the windshields in the upper right corners or behind the rear-view mirrors. Passive installations for receiving signals are placed on car bodies, usually mounted on roofs.

Any antenna is mounted only on a clean surface. For installation, use glue or masking tape, bolts, nuts, locknuts for grounding, a drill suitable for the size of the diameter of the antenna wire. The mounting place must be degreased with a special cleaner.

Fix the devices with glue or masking tape. After installation, wires are laid from the antenna to the radio tape recorder. This is done either around the perimeter of car doors or windows, or directly around the cabin through special holes.

An ordinary car antenna has three wires:

The first is used to ground the device. It attaches to a metal mount on the body. Fix the wire with a bolt, strong nut and lock nut.

The second is used to power the device. It is connected to the wire coming from the radio.

The third is a pin, connect it to a specially designed connector.

Most often, the second wire is combined with the third, connecting the power supply, activating the contact function, the antenna begins to receive a signal.

It is important to choose the right location for the antenna. The car body can be both a kind of indicator of improved signal reception quality and a hindrance. The best place to mount is in the center of the roof.

There should be no foreign objects made of metal near the trap. Combined antennas for receiving various communication signals are best purchased ready-made.

The installation must be protected as much as possible from the effects of the external environment so that oxidation of the contacts does not occur, the parts of the entire structure do not corrode.

An antenna made with your own hands is an effective way of saving money, improving the quality of signal reception, the possibility of technical revision of the radio in your own car.

Car owners who spend a long time behind the wheel of their car strive to provide maximum comfort for themselves and passengers. These comfort features include various multimedia systems with TV, video and audio. However, classical antennas poorly perceive the signal from many TV towers.In such a situation, a do-it-yourself car TV antenna made from scrap materials will come to the rescue. When executed correctly, it will significantly enhance the TV signal and ensure the clarity of the picture and sound.Antennas include quarter-wave vibrators for use with matching devices. A car body is used as grounding, which successfully copes with this role. Most of the circuits necessary for the operation of the device are quite capable of assembling on their own even for a novice radio amateur. But before you make a car antenna with your own hands, you need to consider in what quality it will be used, the type of modulation used, as well as the frequency range that the final product should perceive.There are two main types of antennas:

passive;

active.

Additionally, the device can be equipped with any external power source. The installation method can be divided into external and internal devices. In both cases requires rigid fixation of the device to the car body. Image - DIY auto antenna repair

A combined design is also used. It is classified as an active in-cabin device with external elements that provide high-quality signal reception at decimeter and meter ranges.

You need to know that to improve the signal, antennas are equipped not only with amplifiers, but also with special filters that ensure effective switching with the on-board network.

The operation of the car TV antenna depends on the location of the car, so the device needs to be regularly adjusted to the reception conditions. At a significant distance from the transmission towers, the car owner can install a satellite TV system in the car.

A significant difference between stationary indoor antennas and car antennas is the mobility of the receiving point for cars. The use of household antennas in such a situation will lead to the appearance of a large number of "blind" zones during vehicle maneuvers. This behavior is based on vertical polarization.

When working with a common biquadratic frame, the direction of vertical polarization is not a significant factor, since it is located as vertically as possible.

During the manufacture of an antenna for a car at home, you should pay attention to the following factors:

road inspectors should not have any justified claims to the device regarding body modifications;
the antenna should easily fit and be mounted in the passenger compartment, without creating problems for driving or discomfort for passengers;
the signal should be received as stable as possible at the desired frequencies;
the apparatus must operate with maximum efficiency.

If necessary, the car TV antenna should be quickly and easily dismantled.

It is not always appropriate to use a classic quarter-wave vibrator for built-in autoantennas. It can be difficult to manufacture, and it also has significant dimensions. Problems can also arise when fixing a large object.

The following assembly has shown itself well as a practical design. For it, you need a frame device located under the rear window seal. You need to understand that this form is slightly different from the classic apparatus operating at 27 MHz. Dimensions are compensated by the presence of a condenser in the middle part. It is used to adjust the resonance on the desired channels.

It is necessary with such manipulations to take into account that there are several receiving frequencies: 27 MHz, 65 MHz, 28.2 MHz, 68 MHz. The upper resonance is characterized by the lower broadcast range.

The design of the internal antenna is made according to a simplified scheme:

Copper conductor MGTF 0.5 is used. It is hidden behind a rubber glass seal. In this case, the upper part is made narrower than the rest of the elements.
The location of the poles is obliged to facilitate, if necessary, adding a wire to the capacitor, as well as adding a PK-50 wire to remove the signal.
A 5-25 pF capacitor is mounted on the center of the rear window, with the maximum vertical connection of both cables.
Sealing the wire is done from the end bitten off in the center with wire cutters. There should be no breaks at the opposite end.

Such an antenna is connected to the connectors used for communication equipment.

For the external structure, a Polish-made TV amplifier is usually used. You can also assemble everything yourself. A pair of telescopic antennas provides high-quality signal transmission. They are usually borrowed from old radios during the dismantling of the radio market.

The plastic from the amplifier, to which the magnetic mount is fixed, is suitable as a case. At the next stage, we provide the system with power supply. You will need to take the connector from the active antenna and solder the wire into it. Then we run the cable in such a way that it does not get problematic rubbing or pinching, and finally we fix it in this position.

The wire soldered to the connector is brought out to the socket, which has a connection to +12 V on the multimedia system. We plug the plug into the corresponding "input" of the socket and enjoy a clear image.

The editing process must be approached responsibly to ensure maximum signal quality. The car owner selects the design himself so that it matches the parameters for the built-in TV.

The advantage of the built-in antenna is maximum protection against negative external influences on the device. As a disadvantage, the complexity of dismantling without deformation of the active receiving device is noted.

Alternatively, motorists use a mortise design. The main part of the antenna will be inside, and only the receiving rod is pulled out.

Installation conditions must be observed:

Safe installation and fastening to the car body. In the presence of a carbon fiber coating, the signal will go in weakened. After installation, the maximum protection of metal external elements is carried out against possible future corrosion.
Protection can be done with silicone sealant. It is not advisable to use electrical tape or plastic on the docking. Such procedures will cause condensation to form under the insulation and attenuate the signal.

It is advisable to use high quality metal coated parts.

The system must use a cable. For this, it is customary to carry out installation with a coaxial shielded cable.

You need to know that for installation, one-piece cable pieces without twists or adhesions should be used.

First, you need to stock up on a coil with a sufficient cable length. Be sure to check the cable for breaks with a tester before using it. The signal level largely depends on the quality of the cable.

When laying it along the body of the car, you should follow these rules:

it is necessary to place the cable as tightly as possible to the body of the car kA from the outside and inside the car;
for an outdoor cable, a minimum length limit is set, since it is exposed to negative external influences;
the length should allow the laying without interference, and with a slight sagging;
sharp bends should not be allowed.

In order not to be mistaken with the length, you can first take measurements with a tailor's meter or a construction tape.

Homemade antennas for car TV are unlikely to be able to outrun expensive factory counterparts in quality, however, they will provide sufficient channel reception in almost any city or in a suburban region. They can be assembled from the items at hand that are offered in any used electronics market. The cost of the final product will be significantly lower than the price of the average product in terms of quality.

Today there are many car antennas with different functions. For military purposes, they are used as a means of communication, and for peaceful purposes - as broadcasting channels and navigators. A car antenna is a quarter-wave vibrator with matching devices. This is the signal line, and the ground is the vehicle body. Thanks to this, the signal is received. Quite a simple design that you can do yourself.

First, decide what such a car antenna will serve, what wavelength and type of modulation it should have. These are the three main components that are incorporated into the design.

There are the following antennas for TV and radio in the car: active and passive. Car TV antennas have built-in amplifiers and require a separate power supply.

Depending on where they need to be installed, external and internal ones are distinguished. You need to mount a TV antenna for a car in the same way as a structure for a radio station.

In addition to these car TV antennas, there are combined-type designs.These are the so-called active in-cabin devices, which have external outputs in order to receive high-quality UHF / MV signals.

In order for the signal to become much better, this device may have an amplifier and a filter to connect it to the on-board network.

The car TV antenna needs to be systematically adjusted based on the location of the car at a given time.

The whole point boils down to the fact that the body of the car does not stand still. In this regard, simple terrestrial TV structures used in everyday life will have many dead zones. Long periods of time during maneuvers can occur when there is no reception. This applies only to vertical polarization.

If we are talking about the vertical polarization of simple frame biquad structures and quarter-wave vertical vibrators, then for a car TV antenna there is no difference where the signal will come from, since it is in a vertical state. And now, let's find out what else is useful in the world.

How to make a TV antenna for a car yourself in order to:

there were no complaints from the traffic police officers in connection with the work performed to refine the hull;
it could be located in the cabin;
reliably received signals at the radio frequency;
had a high efficiency (since it should act on the transmission).

A simple quarter-wave vibrator doesn't work very well in this case. It is difficult to manufacture, and its dimensions are rather big. It is difficult to fix - it will interfere with the movement of the car.

Here's what motorists could come up with for cars. Take the frame device to be laid directly under the glass seal at the back. Of course, it will have a narrowing in the upper part and it will not have exactly the dimensions that are needed at a frequency of 27 MHz. Because of this, a capacitor is located in the center, with which you can tune the TV antenna for a car into resonance on the desired channel. It is important to take into account that there are several receiving frequencies, for example:

27 and 65 MHz;
28.2 and 68 MHz.

Upper resonance refers to the lower broadcast range. The car TV antenna has a not very complicated circuit:

To create an antenna, use the MGTF 0.5 wire. It should run along the edges of the rear window in a trapezoidal shape. The upper part needs to be done narrower.
The poles should be positioned so that you can easily add wires for the matching capacitor, as well as the RK-50 cable for removing the signal.
In the center of the rear window, it is necessary to fix a capacitor (5-25 pF), to which both cables must go strictly vertically.

The wire must be soldered on the side where it will be cut in the center. There should be no breaks at the other end.

This, in general, is all. The car TV antenna is connected through a connector used with communication equipment.

You can assemble the external TV antenna in the car yourself. As a basis, you use a Polish TV design as an amplifier.

In order for the signal to pass well, it is necessary to fix a pair of telescopic antennas from the radio receiver (such devices can be purchased on the radio market). The housing for the construction can also be taken from a Polish device, which can be fixed on a magnetic mount from the antenna of its predecessor. Now the question arose, how to provide power to the amplifier? It's pretty simple - just like on a stationary TV. We take the active TV antenna connector and solder the wire to it. Then we pass the cable from the TV antenna so that it is not pinched, could not rub in. Screw it to the connector.

The wire soldered to the connector must be connected to the +12 output on the radio, which will turn on the amplifier or active antenna. You have to plug the plug into the jack and enjoy.

If you correctly install the TV antenna for the car, then you will receive high-quality signal reception. Therefore, the installation must be taken very seriously.

What kind of design you choose will depend on your desires.

The main advantages of a TV antenna installed inside the passenger compartment are its long service life and protection from all kinds of environmental influences. The downside is the impossibility of removing it without damaging the foster mustache.

When installing an outdoor TV antenna for a car, it is best to choose a flush-mounted design. It will be under the protection of the car body (all except for the receiving rod).

The main conditions in the process of fixing the external TV structure:

It is necessary to ensure a secure fit with the vehicle body. If the body has a carbon fiber coating, the signal will not go well.

You can use silicone sealant for protection. Do not wrap the contacts with electrical tape and do not put plastic containers on the antenna. It will worsen its condition, since condensation forms under such insulation.

In order for your design to work, it must be connected using a cable. Coaxial shielded cable is used in outdoor and indoor structures.

Do not twist or solder the extension cable, as you can completely render it unusable. It is best to get it ready-made and, of course, do not forget about checking the connectors. The quality of the incoming signal will depend on how high-quality they are.

Be very careful when routing the cable to the receiver, observing the following important rules:

the cable should be located close to the car body from the outside and inside. Do not let it sag or pull it tight;
leave a minimum cable length on the outside. So, he will not be affected by the external environment;
try not to have excess cable. But if they are, then do not twist or bend them. Try to position them neatly near the receiver.

Homemade gadgets won't have long range or fancy tricks, but it can match some proprietary roof-mounted models with great heights. She will be in place both in nature and in the city.

There is no need for a matching device yet. And this is difficult, since in addition to accurately keeping the number and steps of the turns, it is necessary to find the required wire thickness. All this is necessarily sealed and requires the purchase of many auxiliary materials.

Sometimes buying an antenna for your car and installing it is more expensive and time-consuming, but you end up with lower reception quality. And in the designs described above, everything is simple, and many motorists will be able to assemble them.

How to make a TV antenna for a car yourself can be found in the following video:

Video (click to play).