A Miniaturized Dual-Band Implantable Antenna with Improved Impedance Matching via Shorting Vias and CSRRs

Implantable antennas represent a significant advancement in wireless technology for medical applications, supporting Implantable Medical Devices (IMDs) with various essential functions. To meet the stringent requirements of IMDs, such as compact size, biocompatibility, and structural integrity, implantable antennas must be optimized accordingly. This research addresses these challenges by employing the Defected Ground Structure (DGS) miniaturization technique, combined with the integration of Complementary Split Ring Resonators (CSRRs) in a dual-band antenna design, to achieve a small, multifunctional antenna. The proposed antenna operates within the frequency bands of 2.4–2.48 GHz for Wireless Power Transfer (WPT) and 1.395–1.4 GHz for Wireless Medical Telemetry Service (WMTS). Impedance matching is critical for optimal antenna performance, which is facilitated in this study by the use of shorting vias. These vias not only aid in achieving impedance matching but also contribute to the miniaturization process. The resulting antenna, with dimensions of 9.3 mm × 8.75 mm × 0.635 mm, demonstrates a size reduction of up to 90% through CSRR-based miniaturization. Furthermore, the application of shorting vias has proven effective in improving impedance matching, resulting in a return loss value within the acceptable range despite the dual-frequency operation.