A miniaturized dual-port circularly polarized MIMO patch antenna for SAR-compliant wearable X-band communication systems.

Wearable communication systems operating at X-band demand antenna designs that simultaneously satisfy stringent miniaturization requirements, maintain stable circular polarization, support MIMO diversity, and ensure electromagnetic safety for body-worn deployment. Existing designs in the literature largely address these challenges in isolation, with most reported X-band circularly polarized antennas remaining physically large and lacking rigorous wearable safety validation. This paper presents a compact dual-port circularly polarized MIMO antenna specifically engineered for wearable X-band applications in the 9.0–9.3 GHz range. The principal novelty lies in the simultaneous achievement of ultra-compact form factor, stable circular polarization, effective port isolation, and full SAR compliance within a single passive, single-layer architecture — a combination absent in prior art. Circular polarization is realized through geometry-driven feed offset and patch curvature without external matching networks or multi-feed structures, significantly simplifying the design. The antenna demonstrates strong MIMO diversity performance with low envelope correlation, confirming spatially uncorrelated radiation despite compact inter-element spacing. On-body SAR evaluation using a realistic hand model confirms compliance with international safety standards, validating the design for prolonged wearable use. Simulated results are experimentally verified, with close agreement across all key performance metrics. The proposed antenna advances the state of the art by delivering a practical, application-driven solution that integrates miniaturization, polarization stability, MIMO capability, and wearable safety — making it suitable for next-generation body-centric X-band communication platforms.