SAR measurements for back cover mobile antennas

We compare different low-profile antenna prototypes designed on the back cover of mobile devices around 2 GHz. Especially, we focus on controlling the specific absorption rate (SAR) without sacrificing the antenna efficiency. In addition, we study techniques to reduce the size of the antenna. We compare a traditional patch antenna, a sophisticated SAR-optimized design, and a patch minimized with a matching circuit. All these three options are manufactured. The measurement results show that SAR values can be decreased remarkably without compromising the antenna performance if exposure effects are taken into account in the design.