mmWave Wireless Power Transmission to Flexible Rectennas in Absorptive and Reflective Media

Millimeter-Wave (mmWave) wireless power transmission (WPT) can provide theoretical improvements to the end-to-end link efficiency compared sub-6 GHz bands. However, mmWave propagation in the WPT is yet to be explored. Herein, we present the first evaluation of a broadband mmWave rectenna on a lossy phantom based on radiation absorbing material (RAM). The ground reflection is observed over distance from a 20 dBi horn antenna with a 1 W input around 23 and 28 GHz, where the effect of multi-paths reflections is demonstrated and compared to a varying input from the generator. A DC power output over 10 µis measured at 15 cm from a 51 dBm source, showing the potential for meters-range mmWave wearable WPT with the licensed 5G 75 dBm EIRP levels. It is concluded that the electromagnetic (EM) environment and propagation media can have significant influences on mmWave WPT requiring novel signal and EM co-design.