What is the gain of the antenna?
Gain is one of the main indicators of the antenna. It is the product of the direction coefficient and the efficiency, and is the performance of the antenna radiating or receiving the wave. The choice of gain depends on the requirements of the system design for the coverage area of the radio wave. In short, under the same conditions, the higher the gain, the farther the distance of the radio wave travels. Generally, the base station antenna uses a high gain antenna, and the mobile station antenna uses a low gain antenna.
What is the voltage standing wave ratio?
When the antenna input impedance and the characteristic impedance of the feeder are inconsistent, the generated reflected wave and the incident wave are superimposed on the feed line, and the ratio of the maximum value to the minimum value of the adjacent voltage is the voltage standing wave ratio, which is to check the transmission efficiency of the feeder. The basis of the voltage standing wave ratio is less than 1.5, the voltage standing wave ratio at the working frequency is less than 1.2, the voltage standing wave ratio is too large, the communication distance will be shortened, and the reflected power will return to the transmitter power amplifier part, and it is easy to burn the power amplifier tube. Affect the normal operation of the communication system.
V.S.V.R. 1.0 1.1 1.2 1.5 2.0 3.0
Reflected power % 0 0.2 0.8 4.0 11.1 25.0
Transmission power % 100 99.8 99.2 96 88.9 75.0
What is the directionality of the antenna?
The antenna has different radiation or receiving capabilities in different directions of the space, which is the directivity of the antenna. The direction of the antenna is usually measured by using a pattern. On the horizontal plane, the antenna that radiates and receives no maximum direction is called an omnidirectional antenna, and the antenna with one or more maximum directions is called a directional antenna. The omnidirectional antenna is mostly used in the center station of point-to-multipoint communication because of its non-directionality. Since the directional antenna has the largest radiation or receiving direction, the energy is concentrated, and the gain is higher than that of the omnidirectional antenna, which is suitable for long-distance point-to-point communication, and at the same time, because of the directionality, the anti-interference ability is relatively strong.
How to understand the working bandwidth of the antenna?
The electrical parameters of the antenna are generally related to the operating frequency, and the frequency variation range allowed by the electrical parameter index is guaranteed, that is, the operating frequency bandwidth of the antenna. Generally, the working bandwidth of the omnidirectional antenna can reach 3-5% of the operating frequency range, and the working bandwidth of the directional antenna can reach 5-10% of the operating frequency.
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