A Compact Frequency-Reconfigurable Conformal Antenna for Sub-6 GHz Body-Centric Health Monitoring Applications

Abstract

This work presents a compact, lightweight, and conformal frequency reconfigurable (FR) microstrip antenna designed for Sub-6 GHz body-centric wireless health monitoring systems. The antenna is designed on a Jeans fabric substrate with the dimensions of 0.367 λ0 × 0.275 λ0 × 0.0128 λ0 (λ0 being the free-space wavelength at the lowest frequency) to ensure conformability and mechanical flexibility. Two PIN diodes are integrated at different locations in the geometry, and by varying their biasing conditions, the antenna can be reconfigured to operate at multiple resonant frequencies including 3.2 GHz, 3.4 GHz, 4.6 GHz, 4.7 GHz, 4.83 GHz, 6.7GHz, and 7.0 GHz, thereby supporting for WLAN, LTE, WiMAX, ISM, and 5G communication bands. The critical parameters of the structure, such as reflection coefficient, gain, radiation efficiency, surface current distribution, and radiation patterns are evaluated under different diode switching states. Additionally, mechanical robustness is examined by varying the bending radius, while the electromagnetic safety is validated through specific absorption rate (SAR) analysis conducted using a human hand phantom. The SAR values of 0.106 W / kg at 3.2 GHz and 0.097 W / kg at 4.25 GHz are well below the threshold of biological safety, confirming the suitability of the proposed design for wearable healthcare and multifunctional communication applications. © 2025 IEEE.