A Novel Compact MIMO Antenna for Enhanced Leadless Implantable Pacemakers

This letter presents a new miniaturized multiple-input multiple-output (MIMO) implantable antenna based on meandered resonators, designed for biomedical applications that require compactness and enhanced data transmission rate. The suggested MIMO antenna functions at 2.45 GHz and occupies a volume of$4.7 \times 4.5 \times 0.12$mm$^{3}$, making it among the most compact designs reported in this category. Size reduction is achieved using meandered lines. The proposed MIMO antenna consists of dual radiating elements sharing the same ground plane and are spaced 0.5mm apart. Designed for implantation at a depth of 30 mm within the anatomical environment of the human heart, it is a promising candidate for leadless pacemaker applications. The antenna was fabricated and tested, achieving an isolation greater than 22dB, which confirms excellent MIMO characteristics. Key parameters, including the envelope correlation coefficient (ECC) and diversity gain (DG), were also evaluated and exhibited favorable values, ensuring reliable MIMO operation. It exhibits omnidirectional radiation with spatial diversity. Specific Absorption Rate (SAR) evaluation is conducted using a human tissue environment to verify compliance with safety standards. The results validate the antenna's suitability for implantable applications.