With the rapid development of technology, wireless mobile communication devices have been widely used in people's daily lives. A wireless mobile communication device (such as mobile phone) is usually provided with an antenna device for receiving and transmitting wireless signals. When a user is using a mobile phone for communication, the user's head is close to the antenna device of the mobile phone and may be exposed to electromagnetic radiation. In the international standard, mobile phone electromagnetic radiation is measured in units of specific absorption rate (SAR), which represents the absorbed power of body per kilogram per unit time and is in units of W/kg. In Taiwan, for example, the national communications commission (NCC) limits that the mobile phone SAR must be under 2.0 W/kg, identical to the European standard; and the US federal communications commission (FCC) limits that the mobile phone SAR must be under 1.6 W/kg. Thus, for the industry, there is a need to design an antenna device as well as a communication device complying with the SAR legal limits.