A dual-band omnidirectional rectenna for radio-frequency energy harvesting applications

-This paper proposes a dual-band flexible omni-directional rectenna for radio frequency energy harvesting (RFEH) applications. The rectenna is developed for WLAN/Wi-Fi (2.4 GHz) and 5G (3.5 GHz) bands. First, a dualband impedance matching network is introduced, and its operating principles are analyzed in detail. The network is applied to design the rectifier, followed by fabrication and measurement of the rectifier operating at 2.4/3.5 GHz. At an input power level of -10 dBm, the overall radio frequency (RF) to direct current (DC) power conversion efficiency (PCE) reaches 27.1 % at 2.4 GHz and 20.0 % at 3.5 GHz. Then, a wideband omnidirectional monopole antenna is realized as the receiving antenna for the designed rectifier. The antenna broadens its operating bandwidth by utilizing a tapered microstrip feed and etching a cross-shaped groove on the ground plane. Measured results indicate that the antenna can capture RF energy omnidirectionally within the bandwidth of 2.2-6 GHz, satisfying the demands of the rectifier. Lastly, the prototype of the rectenna is fabricated and tested by integrating the rectifier and monopole antenna into a low-profile design. The experimental results demonstrate that the proposed rectenna is competitive in terms of PCE, flexibility, and compactness. This indicates its enormous potential for numerous battery-free or low-power applications in the real world.