A Circularly Polarized Implantable Rectenna for Microwave Wireless Power Transfer

A circularly polarized implantable antenna integrated with a voltage-doubled rectifier (abbr., rectenna) is investigated for microwave wireless power transfer in the industrial, scientific, and medical (ISM) band of 2.4-2.48 GHz. The proposed antenna is miniaturized with the dimensions of 7.5 mm x 7.5 mm x 1.27 mm by etching four C-shaped open slots on the patch. A rectangular slot truncated diagonally is cut to improve the circular polarization performance of the antenna. The simulated impedance bandwidth in a three-layer phantom is 30.4% (1.9-2.58 GHz) with |S-11| below -10 dB, and the 3-dB axial-ratio bandwidth is 16.9% (2.17-2.57 GHz). Furthermore, a voltage-doubled rectifier circuit that converts RF power to DC power is designed on the back of the antenna. The simulated RF-to-DC conversion efficiency can be up to 45% at the input power of 0 dBm. The proposed rectenna was fabricated and measured in fresh pork to verify the simulated results and evaluate the performance of wireless power transfer.

Automated summary

This study investigates a circularly polarized implantable antenna integrated with a voltage-doubled rectifier for microwave wireless power transfer in the industrial, scientific, and medical frequency band. The antenna is miniaturized by etching slots on the patch and a voltage-doubled rectifier circuit is designed on the back of the antenna for converting RF power to DC power. The experimental results show that the proposed antenna performs well and can be used for wireless power transfer.