The constant payment of monthly fees for the use of satellite or cable television services forces users to look for other ways to watch television programs. For owners of television receivers with a built-in digital tuner, the best option may be to receive terrestrial digital television. This becomes relevant due to the fact that in the very near future Russia is planning to completely abandon TV broadcasts in analog format and switch to digital broadcasting. The correct choice of the receiving antenna has a great influence on the quality of viewing television programs. In large population centers near transmission centers, users often prefer amplified indoor antennas. You can find out how to choose it correctly in the article.
Types of television indoor antennas
By the appearance of television antennas, you can determine its main parameters. These include:
- range or frequency band, inwhich the antenna works;
- antenna gain.
Frequency and wavelength are directly related. Broadcasting of television programs is carried out in the range of meter and decimeter waves. The geometric dimensions of the elements that are part of industrial or home-made antennas are related to the wavelength of the received signal. The higher the frequency or the shorter the signal wavelength, the smaller the geometric dimensions of the antenna design elements.
The range of meter waves of television broadcasting (channels 1-12) corresponds to wavelengths from 5 meters to 1 meter. Vibrators of this range are made in the form of "whiskers", the length of which can be changed depending on the number of the active channel.
This design corresponds to a meter wave antenna. Decimeter waves on which digital television broadcasts are broadcast (channels 25-60) correspond to a wavelength from 1 meter to 10 centimeters. The antenna elements of this range are open frames, rings, elongated ellipses with a set of horizontal plates or metal rods attached to a common traverse. The length of each of them does not exceed (10-30) cm.
The presence of only such structural elements allows us to call the antenna decimeter. The all-wave antenna is a combination of both meter and decimeter antennas.
There are no special indoor antennas with an amplifier for digital television. Broadcast broadcast standardDVB-T2 in Russia is carried out in the decimeter wave range. For reception, any antenna of this range is used together with a decoding digital television tuner.
Antenna gain (without amplifier) can be estimated by the number of elements attached to the horizontal traverse. A larger number of horizontal elements corresponds to a higher gain value. The presence on the traverse of the grating located behind the vibrator (frame, ellipse) significantly increases the gain of the decimeter wave band antenna.
Application of Antenna Amplifier
Indoor antennas with amplifier for TV belong to the class of active antennas. The antenna itself does not amplify the received signal. The value of its gain shows the ability of the antenna to concentrate the energy of the received signal in the direction of the source of useful radiation, while reducing the intensity of signals from other directions. It is directly related to the directivity, which is determined by the design of the antenna. The gain value is expressed in decibels (dB) and is a relative value. A value of 1 dB corresponds to the gain of a vertical whip vibrator that receives signals from all directions. Antenna amplifier amplifies all signals that come to the antenna (receiver) from any direction.
Its main purpose is to reduce signal attenuation in the cable that carries the received signal toTV.
When choosing a room antenna with an amplifier for a TV, the buyer should first of all pay attention to the design of the antenna itself. The accompanying documentation provides the values of the total coefficient (including the amplifier). It is worth paying attention to the diameter of the cable connecting the antenna to the TV plug and its length. A larger cable diameter corresponds to a smaller signal attenuation value in it. The length should correspond to the location of the indoor antenna with an amplifier to ensure the best TV signal reception. Amplifier efficiency increases with cable length.
Connecting an indoor antenna with an amplifier
Any amplifier incorporates active elements (transistors) that require a DC power source for their operation. Structurally, the antenna can have an amplifier built into its housing, or it can be made as a separate device. In the first case, the housing of the active antenna must have a connector for connecting a separate mains voltage adapter.
When using a stand-alone antenna amplifier, power is connected to it through a connector on the case, and it is connected to the antenna with a television coaxial cable through a high-frequency connector. The other RF connector on the amplifier is used to connect it with a coaxial cable to the TV's antenna input.
Features of using indoor antennas with amplifier
Active antennas should be usedwhen the television receiver is more than 5 kilometers away from the transmitting center, taking into account the terrain and the presence of dense buildings in the path of radio wave propagation. The location of the antenna in the room is chosen empirically. With a limited length of the antenna cable, an indoor TV antenna with an amplifier can be placed near a TV located near a window directed to a television center (repeater). Do not forget about the need for a power outlet to power the antenna amplifier. A large gain does not always lead to better reception in urban environments.
Conclusion
After reading the material presented in the article, the interested reader will be able to choose from a large number of indoor antennas with an amplifier that the trade offers, which will provide reliable reception of television programs with high quality. The location of the indoor antenna is determined empirically for each specific case.
