A Dual-Band Multi-Linear Polarization Reconfigurable Antenna for Body-Centric Wireless Communication Systems

A novel dual-band multi-linear polarization reconfigurable (MLPR) antenna for body-centric wireless communication systems (BWCS) is presented in this paper. The design comprises five symmetrically arranged multi-branch radiating units, each integrating an elliptical patch and curved spring branch for the Medical Implant Communication Service (MICS) band (403-405 MHz), and a pair of orthogonal strip patches for the Industrial, Scientific and Medical (ISM) 2.45 GHz band (2.40-2.48 GHz). By selectively biasing PIN diodes between each unit and a central pentagonal feed, five distinct LP states with polarization directions of 0∘, 72∘, 144∘, 216∘, and 288∘ are achieved. A dual-line isolation structure is introduced to suppress mutual coupling between radiating units, ensuring cross-polarization levels (XPLs) better than -15.0 dB across the operation bands. Prototypes fabricated on a 160×160×1.5 mm³ substrate demonstrate measured |S11|<-10 dB across 401-409 MHz and 2.34-2.53 GHz and stable omnidirectional patterns despite biasing circuitry perturbations. The compact form and robust dual-band, multi-polarization performance make the proposed antenna a promising candidate for implantable device wake-up signals and on-body data links in dense indoor environments.