A Miniaturized UHF-Band Rectenna for Power Transmission to Deep-Body Implantable Devices

Abstract

This paper presents the design, simulation, and fabrication of a 50 Ohm miniaturized rectenna for wireless energy harvesting for leadless pacemakers. The paper evaluates the performance of each section separately and also while cascaded. The system is designed to work at ultra-low RF input power. When the rectenna is placed 5 cm away from the body surface in simulations, the amount of received power is approximately -20 dBm. The proposed antenna is a miniature spiral PIFA with circular polarization at 673 MHz. The measured results, in and outside sheep's fat tissue, show that about 15 MHz bandwidth can be realized with \vert S 11\vert below -10 dB and an axial ratio below 3 dB. Two types of rectifiers are fabricated and compared to choose the best one for such a system. Then, unlike most other researches which selected the doubler rectifier structure, this paper uses a single-diode rectifier structure at this power level. The rectenna can be encapsulated in a cylinder with a radius of 5 mm and a height of 3.2 mm. The efficiency of the rectenna reaches 40% at -20 dBm input power.