Photolithographically fabricated FR4-Based miniaturized implantable antenna with geometric tuning for biomedical telemetry in the MICS band

Abstract

This work reports the design, fabrication, and validation of a miniaturized circular monopole antenna for implantable biomedical telemetry in the MICS band. The antenna is built on a single-layer FR4 substrate and encapsulated with a PDMS biocompatible coating, enabling low-cost and scalable fabrication using standard photolithography. Key parameters such as conductor spacing, trace width, shorting element placement, and ground plane geometry were optimized to achieve compact size and stable impedance. Full-wave simulations predicted resonance at 406 MHz with a return loss of −34.23 dB, radiation efficiency of −29.59 dB, and gain of −27.91 dBi. Measurements in tissue-mimicking phantoms and porcine skin confirmed a return loss of −24.82 dB and gain of −27.94 dBi, closely matching simulations. Specific absorption rate analysis verified compliance with IEEE C95.1–1999 safety limits at 193 mW input. The proposed design integrates material choice, geometric refinement, and planar fabrication, providing a reproducible platform for next-generation implantable systems.