Analysis of Human Head Interaction in Handset Antennas Using Ground Plane Corrugation

Abstract

This paper presents a novel approach for designing a mobile antenna with a Low Specific Absorption Rate (SAR). First, the relationship between the electric field and the SAR value is constructed based on the Poynting Theorem studied in the near-field interaction area. Then, the relationship between the surface current and the magnetic field was examined, establishing a connection between the SAR and the surface current on the ground of the antenna. Next, the interaction mechanism of the radiation fields of the antennas with nearby human tissues was studied using electromagnetic boundary conditions derived from Maxwell’s equations. The approach of reducing the antenna radiated electric field was proposed by directly amending the antenna surface current, thereby reducing the SAR levels in human tissues. Finally, three low-SAR antennas are designed according to the proposed approach. This approach was tested using three different antennas. A 3.6 GHz Planar Inverted-F Antenna (PIFA), 1.8 GHz Meandered Planar Inverted-F Antenna (M-PIFA) and 2.4 GHz M-PIFA. The simulation and measurement results of these low-SAR antennas show good impedance matching in the operating frequency range. The peak values of the 10 g average SAR of these three antennas are reduced by more than 30% without compromising the efficiency, maintaining convenient impedance matching at the operating frequency, and without enlarging the antenna dimensions. The measurement was accomplished using thermal analysis and compared with simulation analysis, which proved the validity of this approach as a guide for low-SAR mobile phone antenna design.

Keywords

• PIFA
• M-PIFA
• SAR
• mobile phone antenna
• antenna radiation efficiency
• corrugation