Here you can find your own jammer

Mary Jane had previously taken steps to prevent their use, including buying cell phone jammers, devices that cut off service. He said the device is considered illegal, but no one in the United States has been charged with owning such a device. When buying the signal jammer, he talked to nearby teachers, who were fully supportive. The jammer was older and less effective. At best, it could only block 3G signals, and students with smartphones could still use WiFi. So I bought the latest multi-function jammer.
The school installed cell phone jammers in the dormitory building. This is an act of internal control, which is a good thing. Nowadays, most mobile phones are smartphones. Many students stay up late to play with their phones. The next day's class is very spiritless, affecting learning. After installing the jammer, students will not stay up late and will be more spirited the next day.
Almost every student in the school now has his or her own mobile phone. What's worse is that mobile phones have become a "weapon" for many students against teachers. During the course of teaching, we found that most students use their mobile phones to surf the Internet. Many students tend to listen to music or play video games in class. I often talk in class, and my mobile phone suddenly rings, and I get distracted. Worse still, some students use their phones to help them cheat on exams. It has been reported that the new phenomenon of "cyberbullying" refers to students using text messages and social networks to electronically torture others while listening to lectures.
So you need a phone jammer
Since classrooms are usually small in size, we recommend using a 3G/4G phone jammer, which is very convenient to carry and use. Just press a button to turn it on. Of course, you don't have to worry about emergencies where someone needs to make a call. They can walk out of the classroom to make a call without disturbing others. Or, you can turn off the jammer device only when needed. If you have a small space, you can buy a handheld jammer, and if you have a larger space, you will need a desktop jammer.
Interference Signal Attenuation
The signal strength of the wireless signal gradually attenuates during transmission. Since the receiver can only receive and identify wireless signals with signal strength above a certain threshold, if the signal is attenuated too much, the receiver will not be able to identify the wireless signal. The following are some of the main common factors that affect signal attenuation.
When electromagnetic waves propagate through the air, the signal strength gradually attenuates and disappears as the transmission distance increases. The attenuation in the transmission path is the path loss. Although it is impossible to change the air attenuation value or transmit wireless signals by avoiding the air, the transmission distance of electromagnetic waves can be increased by appropriately increasing the transmission power of the antenna end and reducing obstacles. The farther the electromagnetic wave propagates, the larger the space that the wireless signal can cover.
Obstacles are most common in wireless network environments and have a significant impact on signal attenuation. Different walls, glass, and doors in daily environments have different degrees of signal attenuation. In particular, metal obstacles can completely block and reflect the propagation of wireless signals. Therefore, in the process of network planning, various obstacles that block APs must be avoided.