Design and performance analysis of flexible 2 × 2 linear planar array MIMO antennas with beam steering for on-body and WLAN applications

This paper introduces an on-body simulation and WLAN low-cost flexible linear planar array four-port MIMO antenna with 9.46 dBi gain and 2.41 GHz operating frequency. Compactness, body closeness, and high gain have been the main design requirements, which are of exceedingly high use in WLAN, WBAN, and Wi-Fi wearable devices. The antenna is fabricated using 0.25 mm thick polyimide of low loss tangent of 0.004 and a 3.8 dielectric constant to offer the electrical performance without compromising structural stiffness. The two-port elements are fed into a linear planar array by a corporate feedline network to ensure maximum directivity and prevent signal loss in body-centric environments. To further improve the characteristics of the radiation, an electromagnetic bandgap (EBG) structure is used for effective main lobe radiation and beam forming in the x-axis plane. The structure is designed from a simulation model of 10 g human tissue, and the SAR is 1.09 W/kg, which meets IEEE C95.1 and ICNIRP wearable device safety standards. The antenna's free-space reflection coefficient is -20 dB and -45 dB with EBG at the operational frequency. The antenna's diversity gain is approximately 10 dBi with an envelope correlation coefficient (ECC) value of less than 0.003, making it effective for element-to-element isolation and MIMO-based on-body communication system compatibility.