Whole-body SAR measurements of millimeter-wave base station in reverberation chambers

Abstract

This paper presents a method for measuring whole-body specific absorption rate (WBSAR) of millimeter-wave base stations (BSs) in a reverberation chamber (RC). The absorbed power in the phantom from the equipment under test (EUT) and hence WBSAR is determined as the difference between the total radiated power with and without the phantom. A chamber transfer function is determined and used to include only the absorption in the phantom due to direct illumination from the EUT, i.e., excluding absorption due to the RC multipath reflections. The measurement method was evaluated at 28 GHz using a horn antenna and a commercial massive multi-input–multi-output BS. The experimental results are in good agreement with simulations. The proposed method allows for measurements of WBSAR within 3 minutes, which is much shorter than traditional approaches. The method is suitable for compliance assessments of BS products with the International Commission on Non-Ionizing Radiation Protection 2020 electromagnetic field exposure guidelines, which extend the applicability of WBSAR as basic restrictions up to 300 GHz.