A low profile and wideband textile metasurface-based circular polarized antenna for wearable applications

Abstract

A wideband, low profile, compact, and Circularly Polarized (CP) slot antenna loaded by a metasurface structure array is introduced for wearable usage. The whole structure is realized using textile materials. By etching two square slots in diagonal geometry and engraving a U-shaped slot off the Co-Planar Waveguide (CPW) ground, CP was attained along with enhancement in the 3 dB-Axial Ratio Bandwidth. The proposed CP antenna radiates from 1.35 GHz to 4 GHz, which is the impedance bandwidth; thus, covering the 2.45 GHz Industrial, Scientific, and Medical (ISM)-band. The Axial Ratio (AR) bandwidth varies from 1.6 GHz to 2.5 GHz. As such, the effective operational bandwidth for the proposed CP antenna is 1.6 GHz to 2.5 GHz. The antenna electrical size is 0.33λ0 × 0.37λ0 at 2.45 GHz, highlighting its compactness. To achieve low Specific Absorption Rate (SAR), a textile-based 2 × 2 metasurface structure array is loaded at the back of the CP antenna. Wideband operation was preserved after the integration process with the advantage of reducing the specific absorption rate by 99%, while achieving gain improvements over the wideband frequency band. Fabrications were conducted manually, yet the tested outcomes agreed with the software-generated results. The designed antenna has very good competitive results compared to the literature antennas.