Customers who know something about 5G jammers will find that the most conspicuous part of a signal shielding device is the large number of antennas. These antennas are arranged in a line. Although they are not too messy, they obviously take up a lot of space. Even if it is a 5G jammer with a built-in antenna, the space occupied by the antenna is almost half of the internal space of the entire device. Then the customer's question comes, why doesn't such a low-power 5G jammer use a combiner to combine all the antennas before outputting?

The reason why customers have such doubts is that they want to reduce the number of antennas, thereby further reducing the size of the 5G jammer and making the device more portable. However, the idea is beautiful, but the reality does not develop completely according to the idea.

Although the large number of antennas seem to have the same length and diameter, in fact, this is just a unified shell of the antennas. If you pull out the rubber sleeves outside the antennas, you will find that the cores of each antenna are There will be obvious differences.

The core length of the antenna is closely related to the standing wave frequency of the antenna, and the standing wave frequency directly corresponds to the working frequency of the antenna. If the frequency deviates, it will directly affect the output of the shielded signal in this frequency band. Nowadays, a 5G jammer usually has more than 10 antennas, which means that the 5G jammer includes at least 10 mobile phone frequency bands. It should be noted that the frequency bands of these mobile phones are definitely not in the same frequency band with each other, so the cores of the antennas corresponding to them must have different lengths.

Going back to the question raised at the beginning, can these antennas of different frequency bands be combined and output? It is possible to analyze theoretically and practically. In reality, there are indeed a small number of such applications. For example, through a two-in-one-out or three-in-one-out radio frequency signal combiner, after combining the signals of two or three frequency bands, a Antenna output. However, there are two prerequisites for adopting this method. The first is to be able to accept the increase in cost, and the increased cost is often several times higher than the cost of a low-power mobile phone 5G jammer. The second premise is: you cannot expect to combine all the antennas into one output, because even if the technical indicators of the combiner can meet the requirements, the indicators of the antennas that are finally used for output must not meet the standards. If all the working frequency bands of the 5G jammer are arranged, it can be seen that the initial range is at least from 700MHz to 3600MHz, so the difficulty comes out: for an omnidirectional antenna with a frequency span of 3GHz, the standing wave frequency needs to meet 700-3600MHz Is there such an antenna? The result is regrettable, and it is obviously unrealistic to realize such a large bandwidth.