A low SAR design of folder type handset with dual antennas

In this study, a folder type mobile phone that has dual antennas was designed to reduce SAR (specific absorption rate) on the human head. One of the antennas is a PIFA (planar inverted-F antenna) that is inserted in the folder case, the other is typical monopole antenna. In order to achieve optimal performance from these antennas, the phone was designed such that the PIFA is operated only when the phone is used near the head with the folder opened. When phone is not used with the folder closed, the monopole antenna is operated in order to prevent deterrence of radiation that happens when the main beam of a planar antenna is directed to the human body. For the design of the folder type mobile phone with dual antennas and SAR calculation, we used a commercial tool based upon the FDTD technique, SAMCAD. The resonance frequency was tuned to PCS band, 1.86 GHz. In this simulation, bandwidths, resonant frequencies and radiation patterns were calculated. 1g-average peak SAR values were also calculated and compared with those of conventional folder-type mobile phones. The radiation pattern and gain measurements are carried out inside an anechoic chamber with metallic paint on the inside of the plastic case.