Design and Evaluation of a Flexible Circularly Polarized UWB Microstrip Textile Antenna for Wearable Applications

Abstract

A novel compact circularly polarized monopole antenna designed for wearable use is presented. This antenna, made from jean fabric, offers flexibility, lightweight properties, and seamless integration into clothing. It measures 25 × 30 × 1.4 mm³ in size. The circular polarization (CP) is beneficial for on-body communications as it enhances multipath resistance, reduces interference, and improves connectivity between sensor nodes. The CP is achieved through an asymmetric stepped L-shaped ground plane and slots incorporated into the radiator. The microstrip-fed hexagonal ring monopole antenna provides excellent impedance matching across a wide frequency range from 3.09 to 11 GHz. The simulated and measured results align closely, with an axial ratio bandwidth of less than 3 dB across the 3.4– 10 GHz range. The antenna demonstrates a gain of 2.8–4.4 dB and efficiency ranging from 65% to 82% within this frequency range. Flexibility testing confirms the antenna's adaptability, and the simulated Specific Absorption Rate (SAR) values comply with FCC regulations, making it well- suited for wearable technology.