Wideband CPW Fed Four Port MIMO Antenna-based Microwave Sensor for Deep Brain Temperature in 5G WLAN Bands

Abstract

Abstract This study presents a wideband CPW-fed four-port multi-input multi-output (MIMO) antenna-based sensor for measuring deep brain temperature inside the human head in 5G wireless local area network (WLAN) bands. The range of desired frequency is from 5.45 to 8.56 GHz. The proposed MIMO sensors cover the 5.8 ISM (industrial scientific and medical) band, IEEE 802.11ax-defined Wi-Fi 6E band (6 GHz), IEEE 802.11p WLAN band (5.9GHz), and WPAN band (7.4GHz). A Coplanar Waveguide (CPW) fed approach on a low-cost FR4 substrate is used in designing the planar antenna. In the operational frequency range, the obtained diversity performance parameters show an envelope correlation coefficient (ECC) of very low value (< 0.05), DG of about 10 (> 9.95), total active reflection coefficient (TARC) less than − 13 dB and channel capacity loss (CCL) about less than 0.125 bits/S/Hz. For deep brain temperature measurements, the proposed sensors provide an electric field of 3.92 v/m and a specific absorption rate (SAR) value of 0.16 w/kg at the 9 mm distance inside the human head Phantom. The proposed sensor is capable of measuring 0.5 0C change in temperature at 10 W of input power for 300 seconds when all four ports are active.