Advantages of using directional antennas for mobile phone signal jammers in the examination room
For a long time, most of the cell phone signal jammers purchased and used by the standardized test centers of various schools are omnidirectional antennas. So why do these mobile phone signal jammers prefer to choose omnidirectional antennas? And if you use a directional antenna, what are the advantages?
The most common omnidirectional antenna used by manufacturers of mobile phone signal jammers in the examination room is the soft whip antenna, whose length is similar to that of chopsticks. The reason for choosing such an omnidirectional antenna is entirely because of its low production cost and easy installation. Simply screw the antenna to each RF module output port of the mobile phone signal jammer in the examination room. Moreover, after the shielded signal is transmitted through the omnidirectional antenna, the directionality is not obvious, and it is in a state of full divergence in all directions, which makes it easier to expand the shielding range of the shielded signal.
However, in the actual installation and use process, the mobile phone signal jammer using the omnidirectional antenna is not as theoretically analyzed. It cannot really exert the theoretical coverage of the omnidirectional antenna. This is because when installed in the test room, the mobile phone signal blocker in the test room cannot be installed directly in the center of the classroom. Usually, it can only be installed on the front blackboard or the two sides of the rear blackboard, or on the walls on both sides of the test room. Because it is a wall-mounted installation, and the wall has a very large attenuation effect on the radio frequency signal, which leads to the shielding signal emitted by the mobile phone signal jammer in the examination room, the real effect is only reserved in a semicircle area. .
If the mobile phone signal jammer in the examination room uses a directional antenna, the coverage of the shielded signal emitted by the directional antenna is generally the same as that of the omnidirectional antenna. However, the advantage of using a directional antenna is that the gain value of the directional antenna is higher than that of the omnidirectional antenna. Compared with the omnidirectional antenna, it can generally increase by at least 3-5dB. The transmit power is increased by an additional 1-2 times (every 3 dB power is doubled). This will further increase the effective shielding radius.
Another advantage of using a directional antenna is that it is relatively easy to control the transmission direction of the signal of the mobile phone signal jammer in the examination room, so that the shielded signal can be avoided as far as possible from places that do not need to be shielded.