A Novel Six-Band Dual CP Rectenna Using Improved Impedance Matching Technique for Ambient RF Energy Harvesting

TLDR

Multiband or broadband rectennas are difficult to design because the rectifying circuit’s nonlinear, complex input impedance makes performance sensitive to input power and load variations. This work introduces a novel six‑band dual‑CP rectenna for ambient RF energy harvesting, featuring a broadband dual‑CP receiving antenna with a 550–2.5 GHz bandwidth and compact size. The design employs an improved impedance‑matching technique together with an annular‑ring structure and novel feeding scheme to reduce size and enhance rectifier and antenna performance under varying conditions. The rectenna covers six frequency bands—including digital TV, cellular, and WLAN—and achieves a constant‑efficiency load range of 10–75 kΩ, harvesting up to 26 µW outdoors and 8 µW indoors, making it suitable for low‑power wireless devices.

Abstract

A novel six-band dual circular polarization (CP) rectenna for ambient radio frequency (RF) energy harvesting is presented. Due to the nonlinearity and complex input impedance of the rectifying circuit, the design of a multiband and/or broadband rectenna is always challenging and its performance can be easily affected by variation in the input power level and load. Therefore, an improved impedance matching technique is introduced, which is aimed to improve the performance of the rectifier with a varying condition. A broadband dual CP receiving antenna is proposed, which has a very wide bandwidth (from 550 to 2.5 GHz) and a compact size. An annular ring structure and a novel feeding technique are employed in order to reduce the size and improve the antenna performance. As a result, the proposed rectenna is the first design that covers six frequency bands, including part of the digital TV and most cellular mobile and WLAN bands in the U.K., while the optimal load range for a constant conversion efficiency is from 10 to 75 kΩ. The measured results show that the maximum harvested dc power of the rectenna in typical outdoor and indoor environments are 26 and 8 μW, respectively; it can therefore be applied to a range of low-power wireless applications.