A Novel Proximity-Coupled Fed High-Gain Circularly Polarized Wearable Antenna for On-Body IoT-Based Defense Applications

In this paper, a circularly polarized textile antenna array specifically designed for defense applications is presented, featuring a simple and easy-to-fabricate geometry that makes it a viable solution at a reasonable cost. The main objective of this research is to investigate the additional resonance produced by the mutual coupling of a 2×2 patch array, facilitating the creation of unidirectional radiation with enhanced circular polarization (CP) bandwidth through a modified-phase proximity-coupled feeding network. To mitigate the adverse effects of antenna performance on the human body, a modified-phase feed network with two dielectric substrates between the top patch and bottom ground is introduced. Additionally, cordura fabric is used as a substrate, enabling integration with clothing while maintaining flexibility and conformability. For the experimental validation, a prototype of the antenna has been fabricated and the measured outcomes demonstrate a wider impedance bandwidth (IBW) of 23.6%, a half-power beam width (HPBW) of 63°, a maximum gain of 10.8 dBic, and a 3-dB axial ratio bandwidth (ARBW) of 11.43%. Additionally, the antenna’s performance remains stable throughout structural deformation on a cylindrical surface and under human body loading. The specific absorption rate (SAR) is significantly lower than the U.S. and EU standards, indicating favorable radiation characteristics. By these findings, the proposed antenna design emerges as a promising candidate for IoT-based defense applications.