I believe everyone is familiar with cell phone jammers. In recent years, various types of jammers have emerged in the market. Everyone claims that their jammers are particularly good, and the information is full of water, so you can't tell the good from the bad.
First point:
Everyone thinks that the greater the power of the mobile phone signal jammer, the farther the shielding effect will be. In fact, this is not entirely correct. Many manufacturers take advantage of the fact that ordinary users cannot detect the actual power and deliberately exaggerate the jammer power for publicity, causing the nominal power index of the equipment to lose its reference value. For a large-scale shielding system, the shielding technology used is decisive for the shielding effect. The advantages brought by advanced shielding technology are far greater than the output power factor of the shielding equipment. (For example, the lighting brightness brought by a 40W ordinary incandescent lamp and an 18W brand energy-saving lamp)
Second point:
If a mobile phone signal jammer uses a directional antenna, it will definitely avoid external interference. This is also incorrect, because the directional antenna covers the main lobe, side lobe and back lobe, and its main lobe coverage angle is defined as the angle when the off-axis power of the main lobe drops by 3db. That is to say, the radiation intensity of the side and rear of the directional antenna is only much lower than that of the main lobe. Therefore, if the space close to the antenna still has considerable shielding power, coupled with the reflection of the shielded building, it will still cause external interference. Moreover, if it is not applied properly, it will cause uplink interference, and its interference range will be larger. Therefore, whether the equipment technology can meet the conditions, the application of the antenna, and the debugging of the system are far more meaningful than whether a directional antenna is used.
The third point:
Everyone thinks that the shielding distance of the mobile phone signal jammer is a hard indicator. In fact, the distance is not a fixed value. It is related to the spatial signal strength and quality. Simply talking about the distance is meaningless. The same meter. The shielding distance is related to the gain of the antenna. The shielding host with the same power uses antennas with different gains, and the distance will be very different. For example, when using an antenna with a gain of 16db, the distance is 100 meters, while when using an antenna with a gain of 4db, the distance is only 25 meters.
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