An All-Fabric Wideband Circularly Polarized Antenna for Low SAR Wearable Applications

A wideband, Circularly Polarized (CP), Co-Planar Waveguide (CPW)-fed, and textile-based slot antenna is presented for low Specific Absorption Rate (SAR) wearable applications. The design operates over the wide-ranging bandwidth of 1.6 GHz to 3.8 GHz; thus, covering the 2.45 GHz Industrial, Scientific, and Medical (ISM)-band. ShieldIt and Felt materials were incorporated for the antenna conductive parts and substrate, with thicknesses of 0.17 mm and 1.5 mm, respectively, realizing a highly flexible antenna. Circular polarization and wideband operation were attained courtesy of the two diagonal square slots and a C-shaped slot engraved in the ground plane. At the operating frequency of 2.45 GHz, the antenna displayed a boresight axial ratio of 2 dB, realized gain of 4 dBic, and radiation efficiency of 80 %. Moreover, it exhibited a wide-ranging 3 dB-Axial Ratio bandwidth of 700 MHz. As a result of the presented antenna specifications and results, it might suit the wearable, wideband, circularly polarized medical applications.