Millimeter-Wave Retrodirective Beamformer Based on Waveguide Rotman Lens

In this paper, a mmWave based wireless power transfer (WPT) System at Ka-band is proposed for powering small devices at range. The proposed WPT System utilizes the Rotman lens to achieve retrodirectivity, which is essential for selective beaming of wireless power to the device of interest. To this end, a waveguide high-gain Rotman lens beamformer combined with an array of horn antennas is designed. The beamformer consists of nine beam ports and exhibits a beam-steering coverage over a range of ±20° in 9 discrete directions with the gain of up to 26 dB.