“…So, different methods and techniques have been proposed to reduce SAR levels in human tissue, such as increasing the distance between the human head and the mobile handset antenna, auxiliary antenna elements, ferrite material, the electromagnetic band-gap (EBG) structures, artificial magnetic conductors (AMCs) surfaces, and metamaterials. As reported in [11,12], the effect of varying the distance between the antenna and user head has been investigated for a PIFA handset antenna, this study has shown that there is a proportional relation between SAR and antenna efficiency.…”