5G Low-SAR Antenna with Spatial Reverse Current Distribution

A spatial reverse current distribution method is proposed for designing mobile phone antennas with low specific absorption rate (SAR) in the human body at all faces of a mobile phone. Firstly, the example of a loop antenna is used to illustrate that the reverse current in one plane produces a strong electric field, which results in a high SAR on one face of the phone, while the face perpendicular to it shows low SAR characteristics. To ensure low SAR at all faces of the phone, a spatial reverse current distribution method is proposed. A metal bezel mobile phone antenna is designed based on the method. It consists of a slot antenna with two open-circuit branches and two symmetric metal patches. The designed antenna has a −10dB impedance bandwidth covering 3.4-3.6GHz with a clearance of 1mm, and the SAR decreased by 36.75%. The measurement efficiency is above 0.45.