For a long time, most of the Exam room jammers purchased and used by the standardized test sites of various schools are omnidirectional antennas. So why do these Exam room 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 jammers in the examination room is a soft whip antenna, which is similar in length to chopsticks. The reason why such an omnidirectional antenna is selected is entirely because of its low production cost and easy installation. The antenna is screwed to the output ports of each radio frequency module of the jammer in the examination room. Moreover, after the interference 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 interference range of the interference signal.

However, in the actual installation and use process, the Exam room jammer using the omnidirectional antenna is not as theoretically analyzed, and it cannot really exert the theoretical coverage of the omnidirectional antenna. This is because when installed in the Exam room, the Exam room jammer cannot be installed directly in the center of the classroom. Usually, it can only be installed on the front blackboard or on both sides of the rear blackboard, or on the walls on both sides of the Exam room. Location, because it is installed on the wall, and the wall has a very large attenuation effect on the radio frequency signal, which leads to the interference signal emitted by the jammer in the examination room.

If the Exam room jammer uses a directional antenna, the coverage of the interference 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. Due to the increase of the gain, this is actually equivalent to the transmission power of the Exam room jammer. An additional 1-2x boost (power doubles every 3 dB). This will further increase the effective interference radius.

Another advantage of using a directional antenna is that it is relatively easy to control the transmission direction of the jammer signal in the examination room, so that the jamming signal can be avoided as far as possible from places that do not need to be interfered.