Bandwidth-Enhanced Compact Circularly-Polarized Wearable Antenna with a Magneto-Electric Dipole

Abstract

A compact broadband circularly-polarized wearable antenna is presented for wireless body area network (WBAN) off-body communications. The proposed antenna comprises two substrates, a semi-rigid substrate with low loss-tangent and a textile substrate, that can boost the antenna performance while maintaining wearer comfort. Initially, a crossed-dipole as a fundamental radiator that radiates a circularly polarized (CP) wave is printed on the semi-rigid substrate. A pair of L-shaped slits are loaded into crossed-dipole arm, which significantly miniaturizes the antenna size. A magneto-electric dipole as a parasitic element is loaded to widen axial ratio bandwidth (ARBW) and impedance bandwidth (IBW). A conductive textile is attached to the textile substrate as the ground plane to minimize the specific absorption rate (SAR). The simulated SAR at 5.85 GHz is below the US and EU limit standards. The proposed antenna has solved typical issues in wearable antenna design such as low gain, low radiation efficiency, large size, and narrow IBW and ARBW, while still providing comfortability to wearers.