A 5.8 GHz high-gain flexible receiving antenna for wireless power transmission

In this paper, a 5.8 GHz, high-gain flexible receiving antenna (FRA) is proposed, which can be used for wireless power transmission (WPT) systems. The FRA is designed by an iterative process and is etched on Kapton, with a coplanar waveguide (CPW) feed. In order to improve the gain of the FRA, an air-gap and a flexible reflector are loaded, and the gain is improved from 2.79 to 9.51 dBi at 5.8 GHz. To validate the stability of FRA, the fabricated prototype uses three configurations of 80, 70, and 50 mm. The impedance matching keeps well, and the gain of the FRA can sustain above 8.96 dBi. In addition, a miniaturized WPT system was built. The measured results show that the proposed FRA has a maximum harvesting efficiency (HE) of 71.3%, and it can maintain the maximum HE above 63% in bending conditions. The lightweight, high-gain, and high HE in various cases prove the huge potential of the FRA in WPT applications.