Many companies take advantage of the fact that ordinary users cannot detect the actual power, and deliberately exaggerate the power of the shielding device for publicity, causing the nominal power index of the equipment to lose its reference value. (For example, the indicators of some low-cost single-board cameras in the security industry may be higher than those of mid-to-high-end box cameras.) In fact, for a large-scale shielding system, what plays a decisive role in the shielding effect is the shielding technology. The advantages offered by advanced shielding technology far outweigh the output power (especially the nominal power) factor of the wifi signal jammer. (For example, the lighting brightness brought by 40W ordinary incandescent lamps and 18W brand energy-saving lamps)
2. Can you avoid external interference by using a directional antenna?
As everyone knows, the directional antenna covers the main lobe, the side lobe and the back lobe, and the main lobe coverage angle is defined as the angle when the off-axis power from the main lobe drops by 3db. That is, the radiation intensity from the side and rear of the directional antenna is only much lower than 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 the directional antenna is used.
3. Is the shielding distance of the device a hard indicator?
1) The shielding distance is related to the signal strength and quality in space. Simply speaking, the distance is meaningless. If the same shielding power is 100 meters away at the weaker -70db, it is only 12.5 meters at the stronger -52db.
2) The shielding distance is related to the gain of the antenna. The shielding host of 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. The above examples are all assumed to be open space (free space theory). If we consider various building environments inside the prison, spatial signal strength, direction and other comprehensive factors, to do a good job of the entire shielding system requires a combination of a large number of application technologies and product technologies. , both are indispensable.