With the continuous development of science and technology, the mobile network has also been updated several times from the initial 2G mobile phone network to the current 3G, 4G and 5G mobile phone signal networks. At the same time, wireless mobile phone signal jammer has also undergone continuous updating.
https://www.jammer-mart.com/high-tech-phone-signal-jammer.html

Mobile phone signal jammers is mainly used in school examinations, college entrance examinations and some venues where the use of communication equipment such as mobile phones is prohibited. With the increase of communication network frequency bands, mobile phone signal jammers have shielded from the original 3-way antenna to 8-way antenna and even more than 10 The road antenna jammer is now the built-in antenna mobile phone signal jammer.
https://www.jammer-mart.com/8-band-handheld-jammer.html
So why do the signal jammers in the examination room choose built-in antenna signal jammers?
First, the built-in antenna cell phone signal jammer has a beautiful appearance and conforms to modern aesthetic conditions.
https://www.jammer-mart.com/10-bands-portable-phone-blockers.html
Second, the built-in mobile phone signal jammer is more environmentally friendly and safer. Before the signal jammer with the external metal shell has been turned on for a long time, the machine will generate a high temperature of 50-60 degrees, which also has certain safety hazards. Zhan Electronics built-in antenna mobile phone signal jammer is made of plastic shell, which solves this problem very well.
https://www.jammer-mart.com/10-bands-portable-phone-blockers.html
Third, the built-in antenna signal jammer is easy to carry and has better practicability, and the repair rate is lower, because the old external antenna jammer often had the antenna lost or damaged. It is very simple and convenient to use and carry in the shield shell. When you need it, you only need to turn on the power to start normal use. You don't need to disassemble the antenna after use, you only need to turn off the power, so it greatly improves the use of effect and later maintenance costs.
https://www.jammer-mart.com/22-antennas-wireless-jammer.html