Modelling of handset antenna interactions with the user and SAR reduction techniques

Today´s mobile phones require proof of compliance to standard limits of the specific absorption rate (SAR), before they can be allowed onto the market. The SAR is a calculation of the power absorbed by tissue, averaged over a mass, resulting from the radiation of the handset. This requirement is set by standard committees worldwide making it a critical design consideration for the handset and antenna. The article presents an investigation which highlights how handset designs employing common elements such as the whip and PIFA (planar inverted F antenna) are very sensitive in their resulting SAR averages when alterations to the structures are included. It is seen that simple changes to the handset model can result in large improvements in the SAR performance.