Televizora antena to dara pats

Examples are known when they made satellite dishes with their own hands. Once the factory, working for the defense industry, released a marriage, the clerks did not invent anything better than the sale to the population through the store of toys: they set up sleds for the little ones. The goods were snapped up instantly when a rumor passed between local radio amateurs: it is possible to buy a satellite dish for TV cheaply. Focus on a fraction of a millimeter shot down, the form factor is not maintained thoroughly, reduced by a pair of dB gain! This fact worried little radio amateurs who received in the hands of the antenna-paraboloids of the decimeter range. Much cooler "wave channels", quarter-wave vibrators. Antenna for tv do it yourself? Easy - if you find a sled nearby. ..

Before you do the antenna with your own hands

First of all, keep in mind: today, public broadcasting is replaced by digital. First of all it concerns television. There are several multiplexes in Moscow, a dozen channels are transmitted on one frequency, the turn of the radio comes. The advantage of the approach is attracted by the possibility to design highly specialized devices that can cope with the reception of a specific frequency. Outdoor antenna for digital television composed of several simple elements, forms a pronounced resonance of the desired wavelength. There is no need to provide broadband, got a significant gain gain. Not necessarily the option to buy a TV with an antenna is perfect.

There is no possibility to improve the design of satellite antennas. The toroidal model, hung with irradiators, looks so-so; there are no equivalents for reception from several spacecraft. A phased antenna array with a deviating beam would be suitable, but today the implementation of the design is not so expensive, simply impossible.

Which antenna to choose for receiving television broadcasting

TV broadcasting masters the UHF range( 300 - 900 MHz), horizontal polarization is used. For fishing, take a paraboloid with a properly tuned feed to find, you will need direct visibility on the telecentre or an exact fit to the re-reflected signal, changed by weather conditions, even wind. It is not accepted to use paraboloids, accepting terrestrial broadcasting. The satellite hangs inexorably on one place, the ground stations periodically adjust the ground stations, it is easy to do with a plate. Direct visibility, of course, must be present.

For terrestrial reception, you need an antenna, the main lobe of the radiation pattern of which is wide enough to catch the signal. At the same time, it is required to limit the reception of parasitic components of multipath, interference of neighboring telecentres, towers. Devices are supplied with various kinds of reflectors, the shape and design are highly dependent on the type of antenna. Distinguish:

• zigzag;
• vibrators;
• wave channels;
• framework;
• traveling wave;
• combined.

Among the multitude of devices, a television outdoor antenna is easier to assemble a wave channel( Udo-Yagi antenna).The device has excellent characteristics, today we will consider the class of devices for receiving television broadcasting.

Receiving antennas class wave channel DIY

Antenna design

First of all, the number of elements. The wave channel has a traverse on which are mounted parallel to each other, starting from the back:

1. Reflector.
2. Active vibrator.
3. Passive vibrators( directors).

For channels in the meter band, you must sacrifice the gain to increase the working band of the device. Achieved by reducing the number of directors.

Looks almost like this:

1. The range below 70 MHz will require one director. It turns out a three-element antenna wave channel. Formed by a reflector, active, passive vibrators.
2. The range below 110 MHz is managed by a four-element antenna, where there are two directors.
3. 170 - 240 MHz, it is customary to catch wave channels with five passive vibrators.
4. 470 MHz and higher( digital multiplexes) - it is recommended to use antennas of 15 elements: a reflector, an active vibrator, 13 directors.

Use antennas for FM radio reception, know: vertical polarization. The elements, which will be discussed below, are perpendicular to the ground. Now sizes. Nodes, except for the active vibrator, are pieces of wire, fixed on the traverse parallel to each other. The active vibrator looks like an elongated rectangle with rounded sides. Angles are straight, in practice, arching out of thick material, it is impossible to do exactly. We distinguish four types of distances in the wave channel:

1. Between the reflector and the active vibrator.
2. From active vibrator to first director.
3. From the first director to the second director.
4. Between other directors.

In practice, the construction itself shows itself perfectly, where the directors have the same length, less than that of the active vibrator. The reflector must be superior in length to each individual. The elements are made of round copper, brass, aluminum wire of circular cross section. It is allowed to use central conductors of 4-core cables. Others will distort the reception, it is allowed to try.

The traverse should be produced from the dacha cutting shovel, high density polyethylene pipe( polypropylene).The elements are fastened across bolted connections, if necessary, long directors are supplied with guides of a strong dielectric( wood).If possible, the elements are located in the same plane, be horizontal.

The mast will settle behind the active vibrator, it is recommended to use one or two inclined struts. Neither should fall into the gap between the first director and the active vibrator. Otherwise, the digital television antenna will work disgustingly, knocked down by signal distortion fasteners.

The mast itself is mounted on steel wire braces. It is permissible to use two sets if necessary. The cable for the television antenna is 75 ohms. The same impedance has the wave resistance of the connectors of plasma and LCD TVs. As a result, the reflection of power is blocked, the masters achieve reliable signal reception with minimal expenditure of energy and technical means. When re-amplifying, reduce gain with attenuators.

Dimensions of a home-made antenna type wave channel

The first multiplex of Moscow falls on the frequency of 559.25 MHz. Let's see what size the antenna will have for a portable TV of the appropriate wavelength. This falls on the 32nd channel of the Soviet broadcasting. The literature indicates the following device dimensions:

1. Reflector length 26.9 cm.
2. Active vibrator length 21.3 cm.
3. Active vibrator height 5 cm.
4. Directors length 20.2 cm.
5. Distance 1 - 11, 9 cm.
6. Distance 2- 7 cm.
7. Distance 3 - 13.1 cm.
8. Distance 4 - 15.8 cm.

The signal is removed from the break of the active vibrator at the bottom. The length of the slot does not matter, for the UHF range it is 1.5 - 3 cm. Now we will have digital television, we made an antenna with our own hands, it remains to be installed in the room or on the roof. It is recommended if you have direct visibility, but the tower is located beyond the horizon, use a compass, a map. Watch directly transmitting station - aim the antenna wave channel, using your eyesight. Further adjustment is made by the maximum signal level( in practice, image quality).After the fixture is fixed, as shown above.

Please note: there is no talk of direct visibility in the city. We will catch the reflected signal coming from absolutely any direction. Even from the opposite location of the telecentre. We'll have to search carefully where the broadcast comes from. In case of unsatisfactory quality, it is recommended to use an amplifier for a television signal that is switched on near the antenna. We'll have to hold the power cable to the roof. Allowed to set the wave channel in the room, the amplifier may not be needed. The main losses are due to the cable, the length is kept minimal. Television aerial room with his own hands is made on the same principle. Mast, extensions are not required. Where to place - a personal matter. Depends on fantasy.

If you use a bracket for a television antenna, it is possible to strengthen a number of wave channels on one mast, this will allow you to receive all frequencies with the maximum quality, to catch broadcasting. Please note, did not discuss in the review matching devices that help to achieve the lowest value of the CWS.In this case, the power will be reflected less. An experienced designer should take care of this himself!