Simulation Of Specific Absorption Rate Measurements Speeds Wireless Design

Specific absorption rate (SAR) is a measure of the amount of radio frequency (RF) energy absorbed by the body when using a wireless device. The Federal Communications Commission (FCC) and other regulatory bodies have adopted limits for safe exposure to RF energy that are expressed as SAR in W/kg. Several companies have developed SAR measurement systems that manufacturers of wireless products can use to physically test SAR associated with their products. In the process of designing an antenna used to validate one of these measurement systems -- the ALSAS-10U (APREL Laboratories SAR Assessment System), designed and developed by the systems team at APREL Laboratories -- there was a need to develop a simulation model along with rules and application that accurately predicts SAR measurement results to within a few percent without the need for significant prototype development and testing. This makes it possible to address SAR compliance problems in the early phases of the design process when problems can be fixed at a much lower cost because much less money has been invested in physical design changes. This article will explain the challenges that were overcome in the development of this model's rules and application for use.