Now almost everyone has a mobile phone, and it has the functions of transmitting information, video, recording, etc., so it is likely to lead to the leakage of important information of some institutions. Many departments have taken measures to install signal jammers to safeguard their own interests. Well, in places where information must be kept strictly confidential, such as government organs, banks, examination halls, and so on. In some important examinations, basically every school will install signal jammers to prevent candidates from cheating. During the final and college entrance examinations, as long as the mobile phone enters the shielded area, it will not receive the signal or the signal is very weak. In addition to these places, signal jammers should also be used in gas stations, because gasoline is easy to volatilize, and the air in gas stations will be mixed with many gasoline molecules, so the sparks generated by open flames or other substances will cause explosions. The mobile phones we use have this safety hazard when making calls or sending messages, which may lead to fire in gas stations.