SAR AND RADIATION CHARACTERISTICS OF A DIPOLE ANTENNA ABOVE DIFFERENT FINITE EBG SUBSTRATES IN THE PRESENCE OF A REALISTIC HEAD MODEL IN THE 3.5 GHz BAND

This study investigates the performance of a dipole antenna above electromagnetic band gap (EBG) substrates with different number of patches to realize a low specific absorption rate (SAR) antenna for a 4G wireless communications system (3.5 GHz band). A cubic head model is used for the initial analysis to estimate the radiation characteristics and the SAR of the antenna. Computational results have shown that the antenna above an EBG substrate could provide a maximum reduction of 81% in the SAR and a radiation efficiency improvement of 10% when compared with the antenna above a perfect electric conductor (PEC) ground plane. However, the antenna above an EBG substrate with a lower number of patches results in a higher resonance frequency and cannot provide sufficient SAR reduction In both the cubic and realistic head models, a similar tendency was observed in the SAR reduction capability of the antenna above the EBG substrates when compared with the antenna above the PEC ground plane. For the realistic head model, the SARs of the dipole above EBG substrates with 20 or 24 EBG patches can be reduced by 16% when compared to the case with 12 or 16 EBG patches. The variability of the SAR in the operating frequency band (|S11| > 10 dB) of the antenna is 5–35% for different EBG substrates.