In current communication world, those controlling the communication technology will become a winner of current information world. Thus, communication devices have become necessary equipment. Since mobile phones are more and more popular, almost everybody has one. However, with the increment of communication traffic, electromagnetic radiation is also filled in the air. But this is harmful to the human body. Especially, the electromagnetic radiation from the mobile phone of user himself (herself) because the radiation from user's mobile phone is very near the body of user, especially the brain.
The current mobile phone system has been advanced to digital mobile phones from early analog mobile phones, the frequency band ranges from 800 MHz to 1000 MHz, recently, 1800 MHz frequency is also included. Such high frequency electromagnetic radiation has a great transmission property. When the mobile phone with a power of 0.5 watt is emitted, it the mobile phone is near the neck portion of user, about 0.2 watt of power will penetrate through the head of the user and is probably produced a bad effect.