A Study on Microwave Power Transfer to Rectangular Antenna for Stratospheric Platform

Stratospheric platform attracts attention as a new communication infrastructure for expanding the communication area in many countries. In stratospheric platform, the unmanned airplanes stay at the stratosphere(an altitude of about 20km) and use as a communication relay station. In this concept, it is important to get a light and stable power supply for long term operation. Microwave power transfer is proposed as one solution. By using radio waves, microwave power transfer can transmit wirelessly and efficiently even at long distances. However, considering the shape of the airplane, it is desirable for the receiving antenna to be an elongated rectangle. An antenna shape such as rectanglar or circular affects the transmission efficiency even though the antenna aperture area is even. Therefore, when the receiving antenna becomes rectangular, it is confirmed that the transmission efficiency improves if the transmitting antenna is elongated according to its shape. Furthermore, we estimate the transmission efficiency including the attenuation of the atmosphere and the rainfall. In addition, since the airplane is assumed to move along the flight path, it is necessary to obtain how much power can be obtained over the entire flight path. Therefore, we also examined the received power in the entire flight path.