Friends who have come into contact with wireless bridges probably know that wireless bridges need antennas. Whether they are built-in antennas or external antennas, antennas are always needed to use them. So why do wireless bridges need antennas? How to choose the right antenna? Professional wireless bridge equipment and solution provider Feng Runda introduce.
Principle of wireless bridge signal transmission: RF signal power output from the transmitter bridge is transmitted to the antenna through the feeder (cable), and then radiated by the antenna in the form of electromagnetic waves. After the electromagnetic wave reaches the receiving location, it is received by the antenna and sent through the feeder. To the receiving bridge. It can be seen that the antenna is a transmitting device of a wireless bridge signal. Without an antenna, the signal of the wireless bridge cannot be transmitted, and there is no radio communication.
There are many varieties of antennas for use under different conditions such as different frequencies, different uses, different occasions, and different requirements. According to different installation methods, it can be divided into built-in antenna and external antenna; according to different signal transmission directions, it can be divided into directional antenna and omnidirectional antenna; according to different frequencies, it can be divided into 2.4G antenna and 5.8G antenna... so much Antenna type, how to choose?
One, built-in antenna and external antenna
1, built-in antenna
Since the antenna and the device are integrated together, they are small in size and easy to install. They are generally used in short-distance wireless transmission systems, and generally the built-in antenna can be used within 5 km. In addition, the gain of the built-in antenna is generally relatively small, and the transmission distance is relatively close.
2, external antenna
The external antenna is generally large. If the transmission distance is relatively long, for example, more than 10 kilometers, it is recommended to use a high-gain external antenna. Generally when multiple video signals are sent (point-to-multipoint) to transmit video signals, if you need to increase the receiving angle, you can use an external antenna to achieve this. Because the angle of the built-in antenna is relatively small, it is not suitable at this time.
Second, directional antennas and omnidirectional antennas
1, directional antenna
In the horizontal direction, it shows radiation in a certain range of angles, and the main radiation range is like an inverted, less complete cone. It is generally used in environments where the transmission distance is long, the coverage is small, the target density is large, and the frequency utilization is high. Directional antenna signals can only be transmitted to the front. The purpose of using a directional transmitting antenna is to increase the effective utilization of radiation power, increase confidentiality, and increase anti-jamming capability.
2, Omnidirectional antenna
That is, in the horizontal direction, it shows that the radiation is uniformly 360°. The radiation range is like an apple. It has non-directionality and is generally used in environments where the transmission distance is near and the coverage is large. Omnidirectional antenna signals are transmitted in all directions. The price is low and the gain is relatively small, generally less than 9 dBi.
Third, 2.4G antenna and 5.8G antenna
The choice of frequency is relatively simple, depending on the frequency of the wireless bridge. If the wireless bridge is 2.4G, select 2.4G antenna; wireless bridge is 5.8G, select 5.8G antenna. Never use a 2.4G antenna for a 5.8G bridge or a 5.8G antenna for a 2.4G bridge, which can cause no signal transmission.
The use of wireless bridges and antennas is very flexible. Different devices and antennas can be selected according to different environments, different point locations, and different transmission distances.
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