Flexible Omnidirectional Circularly Polarized Wrist-Band Array Antenna for Wearable Applications

An all-textile wristband array antenna (WAA) with circular polarization (CP) and omnidirectional radiation is investigated for wearable applications. The proposed WAA is composed of a group of CP patch antennas excited with uniform amplitude and phase, which can be worn on the wrist to achieve omnidirectional radiation pattern and provide wide signal coverage. The considerations about how to achieve omnidirectional radiation and to avoid radiation nulls are studied in detail. The simulated results on the phantom show that the -10-dB impedance bandwidth is 8.3% with a 3-dB axial ratio bandwidth of 3.3%, and the gain variations are less than ±0.7 dB over all azimuth angles. For validation, the flexible prototype was fabricated and tested, and the experimental results reflect that it can work well in the 5.8-GHz industrial, scientific, and medical band.