Conformal Dual-Reconfigurable Antenna System for Reliable Cardiac Biotelemetry with Dynamic Misalignment Adaptation

This paper presents a micrometer-thick conformal on-board antenna with dual frequency and pattern reconfigurability. An on-board microcontroller unit (MCU) controlled PIN diodes with optimized circuit positioning, providing adaptive flexibility with real-time mode switching. The measured antenna exhibits frequency reconfigurability over 2.388-2.467 GHz within the 2.45 GHz ISM band. Meanwhile, pattern reconfigurability enables directional-to-omnidirectional switching and beam steering of 297°-317°and 211°-239°in the E-plane, and 121°-149°in the H-plane. For human safety and wearable-device considerations, the specific absorption rate (SAR) and thermal behavior of the system are evaluated, confirming that operation remains within regulatory safety limits. A systematic xz-and yz-plane bending test over representative body curvatures demonstrates robust mechanical compliance, from the flat state to bending down to a 40 mm radius. Finally, to verify the reliability of the communication link between the proposed external receiver (Rx) antenna and implantable transmitter (Tx) antenna, full-wave S21 simulations under Tx-Rx translational and orientational misalignments show that the proposed reconfigurable Rx antenna can mitigate loss by up to 5.41 dB. The in vitro S21 measurements are conducted using porcine tissue are identical to the simulation results, further verifying the reliability of the Tx-Rx antenna communication link. The reconfigurable antenna-based system has the potential to enhance the adoption and effectiveness of misalignment in cardiovascular implants within Internet of Medical Things (IoMT) networks. Such functionality ensures consistent link quality and stable data throughput in dynamic environments without physically repositioning and antenna retuning.