A Compact MIMO Antenna for WBAN Applications at Millimeter-Wave Frequencies

Wireless Body Area Networks (WBANs) are essential for remote patient monitoring and early disease detection and require real-time data for personalized treatments. Challenges exist in ensuring WBAN reliability and performance, including the development of efficient on-body antennas. This paper presents a multi-input-multi-output (MIMO) antenna for WBANs operating in the millimeter-wave band. The proposed MIMO antenna has a decagonal patch fed by a microstrip feedline on a single-layer substrate. It provides 7.50 dBi gain and 86% efficiency while covering the 28 GHz band. The inter-element isolation is below −20 dB, eliminating the need for mutual coupling reduction techniques. The MIMO antenna has a low envelope correlation coefficient (<0.0025), high diversity gain (>9.98), low channel capacity loss (<0.5), and a low total active reflection coefficient (<−10 dB). The SAR assessment on a human body tissue model yielded a SAR value of 0.0371 W/Kg for 1 g of tissue at 28 GHz, showing that the MIMO antenna is suitable for WBAN applications.