High-Bandwidth Flexible Inkjet-Printed Antenna Design for Microwave Power Transfer Applications

This letter demonstrates an inkjet-printed antenna flexible harvester for microwave wireless power transmission (MWPT). The substrate and radiator are separately based on Polyimide and EGaIn(Eutectic gallium indium alloy, in which the mass fraction of Ga and In are 75.5% and 24.5%, respectively). Based on metal etching, secondary etching is carried out on the substrate to reduce the dielectric constant, the antenna’s quality factor has been reduced, altering the coupling of the patch, thereby increasing the antenna’s bandwidth. Simulation results indicate that at a working frequency of 5.8GHz, after the etching operation, the bandwidth is 5.19-5.92GHz. Simultaneously, within the bandwidth range, the total efficiency has significantly improved, and there is a notable enhancement in gain within the frequency range of 5.3-5.8 GHz. The measurement results indicate that the antenna has a bandwidth of 5.17-5.83 GHz. The maximum captured power is 35.4 mW at 5.7 GHZ, and it can maintain a captured power of over 22 mW under multi-angle incident waves. Under different conformal curvatures, the antenna can still maintain a captured power of over 28 mW. The results indicate that the antenna can be applied to energy reception under flexible conformal conditions, meeting the requirements of future flexible, wideband energy reception applications. This contributes to the field of wireless power transmission to a certain extent.

I. Introduction

Microwave wireless power transmission (MWPT) has garnered significant attention since its proposal in 1964 [1]. As a crucial component of the MWPT system, the performance of the receiving antenna directly influences the overall system’s operational efficiency [2], [3], [4], [5]. With the increasing demand for wireless charging, there is a growing need for antenna flexibility in many smart devices [6] [7]. However, a significant drawback of microstrip patch antennas is their narrow bandwidth, which cannot meet the requirements of multi-frequency and multi-input applications [8], [9], [10], [11], [12], [13]. Therefore, there is a desire for antennas with wide bandwidths, enabling them to receive microwave energy from multiple frequency bands. Additionally, this facilitates frequency matching with rectifying components [14], [15].