A Compact Polarization-Insensitive Rectenna With Harmonic Suppression for Wireless Power Transfer

A compact, polarization-insensitive rectenna based on metasurface (MS) is designed at a frequency of 5.8 GHz. The proposed MS element consists of a subwavelength octagonal metal ring, offering insensitivity to the polarization of incoming waves. This design effectively addresses the polarization mismatch problem encountered in wireless power transfer (WPT) systems. To further enhance performance, a meandered groove is introduced into the octagonal metal ring, effectively suppressing the generated second harmonic from the rectifier diode and eliminating the need for a low-pass filter module within the rectifier circuit. To demonstrate the concept, a prototype of a rectenna is fabricated and measured. Experimental measurements reveal that the conversion efficiency of the rectenna fluctuates within 10% under different polarization angles and has the characteristic of polarization insensitivity. The maximum conversion efficiency measured reaches 66% under a 500 Omega load. Compared with the MS rectenna without harmonic suppression, the conversion efficiency of the rectifier is improved by 1%-4%. These findings indicate that the proposed rectenna is suitable for various polarization scenarios, offering a promising solution for achieving efficient WPT. Index Terms-Harmonic suppression