Antenna amplifier introduction and application

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About antenna amplifier

Antenna amplifiers are also called preamplifiers. They are commonly called Mastheader Amplifiers in English. Some European and American countries are called Pre-amplifier or Antenna Amplifier, AmplifICador, etc. They are ultra-high frequency, wideband, low noise amplifiers for antennas and feeders. It is used to enhance the weak signal caused by the receiving distance too far, compensate the loss of the transmission distance between the antenna and the TV, and ensure the necessary input power of the distributor in the shared antenna system to improve the receiving quality.

When we receive long-distance TV programs or accept high-definition TV programs on the ground, the TV signals are generally weak. In this case, we need to use a multi-unit TV antenna with strong directivity and high gain. We also need to set the antenna as high and empty as possible. The place. If the receiving situation is not ideal enough, an antenna amplifier should be added between the antenna and the TV to improve the receiving sensitivity and stabilize the image of the TV with good sound.

After using the antenna amplifier, it is like adding a "telescope" to the TV. It can zoom in on the weak TV signal received by the antenna, but of course, in the process of receiving, it is not only the TV signal, but also the Noise and interference. Usually the antenna signal can amplify the TV signal to a dozen times or more. The antenna amplifier is actually an oversized high-band amplifier. The receiver channels, frequency range, and overall gain of various antenna amplifiers are different.

When using an antenna amplifier, pay attention to the following issues.

(1) Note the installation position The antenna amplifier usually consists of an amplification part and a power supply. In the case of short antenna feeders (generally using indoor antennas), the antenna amplifier can be placed next to the TV; when the antenna is set high and the feeder is long, the two parts should be placed separately, and the enlarged part is sealed by a waterproof box. After that, it is preferable to be installed at the end of the support rod 1 to 1.5 m from the antenna element, and the power supply portion can be placed near the television, which can improve the signal-to-noise ratio of the television signal.

(2) The channel must match the antenna amplifier. It is divided into two categories: very high frequency and ultra high frequency. The VHF type can amplify TV signals of 1 to 12 channels, and the UHF type can amplify TV signals of 13 to 68 channels. When in use, the antenna amplifier should match the TV channel to be received.

(3) Note that the output impedance of the impedance matching antenna amplifier and the antenna output and the input impedance of the TV should match. The feeder should not be too long, that is, the antenna cannot be placed too high or too far. Otherwise, although an antenna amplifier is added to the television set, the increased signal is severely attenuated during transmission to the television set, resulting in little improvement in reception. In addition, the input and output feeders of the antenna amplifier must not overlap or be placed too close together to avoid feedback or interference.

(4) Must choose the gain of the antenna amplifier of various models is different, generally there are high and low points. High-gain antenna amplifiers typically have a gain of 30 to 60 dB and are compatible with multi-channel Yagi antennas to receive TV programs hundreds of kilometers away. The low-gain antenna amplifier has a gain of 20 to 4OdB and can receive programs dozens of kilometers away. Make the appropriate choices when choosing, but not the higher the gain, the better.

(5) Checking the installation effect If the image received by the indoor large line is inferior and the outdoor antenna can be used to obtain good results, the indoor antenna can still be used after the amplifier. If the viewing effect of the TV is not changed after the antenna amplifier is installed, or if the viewing effect is worse than before, it is caused by an installation error. It should be carefully checked and then corrected according to the correct installation method.

(6) There are good antennas and lightning protection equipment. For example, TV users who use outdoor antennas need to install antenna amplifiers. They must have good multi-unit antennas to cooperate with them, and lightning protection equipment should be installed to prevent lightning strikes.

The evaluation criteria of the antenna amplifier

a small signal noise

Second, the sensitivity is high

Three waterproof is better

Four volumes are smaller

Five metal casings are better

Six power saving

Seven wiring is convenient