Techniques of evaluating high impedance surfaces used for SAR reduction

In this study, high impedance surface (HIS) structures were used to reduce interaction between a wireless antenna and its user. Mushroom and Jerusalem Cross HIS structures were designed for the PCS band (1.8 GHz). The performance of these HIS structures were investigated by surface-wave and reflection-phase methods. A new test method was also proposed to characterize the reflection phase of an HIS by using a GTEM cell. The effects of HIS sheets on antenna performance and the SAR were studied. Results revealed that these HIS structures can reduce SAR values.