A High-Efficiency Inductive Antenna System With a Magnetic Focusing Unit and a Matching Module for Wireless Hyperthermia: Design and Verification

Wireless power transfer (WPT) has emerged as a transformative technology for applications ranging from biomedical implants to remote sensing. However, conventional WPT systems face limitations in power transfer efficiency, and particularly a significant attenuation occurs when high-frequency powers penetrate dense media like biological tissue. This work introduces a high-efficiency antenna system designed for wireless hyperthermia in peripheral arteries, which demonstrates enhanced penetration capability through biological tissues, making it ideal for powering deep-tissue medical implants with medium power (from 1w to 100w). The innovative antenna system comprises a coil, an external ferrite-based magnetic focusing unit (MFU), and an impedance matching module. The optimized leakage-shaped MFU was simulated and found to result in 2.1∼6.6× increase in magnetic field strength. The measured port gain of our antenna system, which reflects the efficiency of WPT, increases by 7.7∼14 dBm compared to the conventional coil antenna. Moreover, the receiver was powered with still 95% of maximum voltage despite a 30° angular deviation, showing adaptability to misalignments. The integrated matching module achieves impedance transformation to 50 Ω at 1.5 MHz. After matching, the reflection coefficient S<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> of the antenna is −30 dBm and the port gain rises up by 32 dBm. In the heating test, a 40% increase in heating rate is achieved. Power transfer efficiency (PTE) is 33-25% and heating efficiency (HE) is 4.6-3.1 °C/W through a 1.5–2.5 cm phantom thickness. The demonstrated enhancement of the proposed antenna system suggests it to be a promising method for in-vivo deep (a few centimeters) wireless hyperthermia treatment.