Compact Wideband Circularly Polarized Wearable Antenna Based on Mirrored and Rotated Dual-Antenna System

A compact wideband circularly polarized antenna is proposed for highly integrated wearable devices. It comprises two pincer-shaped cross dipoles arranged in a mirrored and rotated configuration, encapsulated in transparent silicone and fed by a quadrature coupler. The use of asymmetric pincer structure in the cross dipoles enhances both the impedance bandwidth and axial ratio (AR) bandwidth. Rather than employing a ground plane or metasurface, one set of cross dipoles functions as a reflector, enabling directional radiation with an improved front-to-back ratio (FBR) and contributing to the antenna's compact size. Additionally, the use of silicone as the dielectric medium enhances the antenna's mechanical robustness and resilience to external environmental influences. Results demonstrate that the antenna achieves fractional bandwidths (FBWs) of 42% and 22% for a 10-dB return loss and 3-dB AR, respectively. Within the AR bandwidth, the FBR exceeds 8.0 dB, and the maximum radiation efficiency reaches 73%. The overall dimension of the antenna is 0.43λ × 0.43λ × 0.10λ, representing the smallest size among state-of-the-art wideband CP antennas.