A Study on Microwave Power Transmission System to High Altitude Platform Station Considering Rectification Efficiency

High altitude platform station (HAPS) is a telecommunication platform in the stratosphere and its communication area is expected to expand. Microwave power transmission (MPT) is considered as a stable power for long-term operation of HAPS, regardless of day or night. The MPT system has been studied in detail based on the beam transmission efficiency. However, since the power level differs between the center and the edge of the receiving antenna, the rectification efficiency at the edge is reduced, which may lead to a decrease in the overall transmission efficiency. In this paper, we study the MPT system based on the transmission efficiency, including beam transmission and rectification efficiencies, and also study the necessary radiated power. The results show that even with the rectification efficiency, the average transmission efficiency is higher when the transmission antenna is rectangular and the flight path is circular + straight. In addition, assuming 40 kW of radiated power, more than 2 kW of DC power can be obtained.