A new measurement technique and experimental validations in determination SAR of N-antenna transmitters using scalar E-field probes

This paper presents a measurement technique to evaluate the Specific Absorption Rate (SAR) for multi-antenna transmitters such as a mobile phone or the like. Fundamental analysis of SAR formula for the general case of N antennas and experimental validations for the case of three antennas are presented. The key point of the proposed technique is to measure SAR for some different relative phase combinations of the antennas and estimate SAR for any other relative phase combinations. To determine the maximum SAR value of two-antenna devices, only three measurements are necessary while for three-antenna cases, seven measurements are required. The proposed technique suites well for SAR measurement systems using scalar electric field probes, and experimental validations show that estimated SARs and measured SARs are in very good agreement.