Advanced Post-Processing Technique to Evaluate Specific Absorption Rate (SAR) for a Standard Dipole Antenna

With the progress of Radio communication technology, modern communication devices such as smart phones are packed with more and more frequency bands and different modulations covering 2G, 3G, 4G, 5G, WLAN, Bluetooth, Non terrestrial Network (NTN) and other use cases. Legacy techniques to evaluate the Specific absorption rate (SAR) take a lot of time, human resources and material costs. In this paper, advanced post-processing techniques are combined with near-field measurements to evaluate the SAR of a standard SAR dipole antenna. The results are then compared to measurements on a legacy SAR measurement system and with full wave simulations. The results show very good comparison with just 0.94 dB difference w.r.t reference measurements evaluated for the standard SAR dipole antenna operating at 2.45 GHz frequency. This study demonstrates that the proposed method to use near-field data along with advanced post-processing techniques is reliable and promising. The goal is to use this technique for evaluation of modern communication devices for pre-compliance SAR testing in a more efficient way as compared to using legacy SAR evaluation techniques, which are more time consuming, and require more human and material resources.

I. Introduction

Several contributions have been made to the topic of advanced post-processing techniques in recent years applied to the evaluation of SAR [1]–[3]. The motivation behind this alternative approach is the exponential increase of measurement time with the increase of number of frequency bands that are required for SAR evaluation for modern communication devices (such as smart phones). Legacy SAR measurement technique (e.g [4]) use a single probe on a robotic arm. E-field is measured using the probe within a phantom filled with liquid representing whole body or part of a body with equivalent electromagnetic characteristics. This invasive approach provides accurate measurement of SAR but takes a lot of human effort and time when evaluating SAR for all the frequency bands that are incorporated in modern smart phones.