A Circularly Polarized Implantable Rectenna for Microwave Wireless Power Transfer

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Electromagnetics

Background:

• Microwave wireless power transfer (WPT) is crucial for powering implantable medical devices.
• Efficient rectenna design is essential for effective WPT, especially within the Industrial, Scientific, and Medical (ISM) band.

Purpose of the Study:

• To investigate a circularly polarized implantable antenna integrated with a voltage-doubled rectifier for WPT.
• To miniaturize the antenna while maintaining optimal circular polarization and impedance matching.
• To evaluate the RF-to-DC conversion efficiency of the integrated rectenna.

Main Methods:

• Design and simulation of a miniaturized circularly polarized antenna with C-shaped slots and a diagonal truncated rectangular slot.
• Integration of a voltage-doubled rectifier circuit on the antenna's back.
• Performance evaluation using simulation in a three-layer phantom and experimental measurement in fresh pork.

Main Results:

• The antenna achieved a miniaturized size of 7.5 mm × 7.5 mm × 1.27 mm.
• Simulated impedance bandwidth of 30.4% (1.9-2.58 GHz) and 3-dB axial-ratio bandwidth of 16.9% (2.17-2.57 GHz).
• Maximum simulated RF-to-DC conversion efficiency of 45% at 0 dBm input power.

Conclusions:

• The proposed rectenna demonstrates effective performance for microwave WPT in the ISM band.
• The miniaturized design and efficient power conversion show promise for implantable biomedical applications.
• Experimental validation in pork tissue confirms the simulated performance for real-world scenarios.