Harmonic Reflection Rectenna Capable of All-Polarization Reception for Wireless Power Transfer Antenna Alignment

초록

This paper proposes a novel harmonic reflection (HR) rectenna that simultaneously achieves all-polarization reception and third-harmonic reflection with inherent polarization conversion for wireless power transfer (WPT) antenna alignment. A 90 degrees hybrid coupler integrated with a two-port dual-band multi-polarized antenna enables reception of arbitrary linear polarization (LP) and circular polarization (CP) without mismatch loss, while the third-harmonic signal generated by the diode nonlinearity is reflected through a dedicated third-harmonic control network (3rdHCN) and re-radiated through the same antenna to provide a feedback signal for alignment without additional DC power. A key insight of the proposed design is that each quarter-wavelength branch of the coupler becomes three-quarter-wavelength at the third harmonic, so the 90 degrees phase shift at f0 reverses to 270 degrees ( approximate to - 90<^> ) at 3f0. This reversal inherently converts the CP handedness and rotates the LP direction by 90 degrees, providing physical isolation between the fundamental and harmonic bands without requiring a clear spectrum. Using the third harmonic rather than the second also preserves the strong second-harmonic component for rectification efficiency enhancement. Measurement results show a peak power conversion efficiency (PCE) of 72.3% at 13.3 dBm for LP and 68.2% at 13.7 dBm for CP, with peak conversion gains (CG) of -14.1 dB and -13.9 dB, respectively. The PCE > 50% bandwidth spans 2.15-2.8 GHz for LP and 2.15-2.75 GHz for CP. Free-space system measurements at distances from 0.1 to 1.5 m further validate stable operation as a WPT receiver while providing a reliable harmonic feedback signal for antenna alignment.

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