Solar Power Station/Satellite (SPS) with Phase Controlled Magnetrons

Abstract

USA)[1] and Recent Japanese Models (NASDA[2]; METI[3]; Japan) are among them. Some of them are designed based on a microwave power transmitter with microwave tubes. The electronic tubes such as Klystron or magnetron have high efficiency (>70%) and high power output (over kW). However, the microwave power density at a transmitting antenna element of the SPS is too high ranging from several tens watts/element to a few hundred watts/element. Therefore, we must use a system providing the power from one electronic tube to a single sub-array unit or to insert a power divider with phase shifters between the power device and each antenna element. We refer to this system as a PD-PS system. The sub-array system suffers from little power loss but generates grating lobes when power beam is electronically swung. As the microwave power from the SPS is huge, we must lower the grating lobe level to satisfy the requirement for the compatibility with the existing communication system. On the other hand, the PD-PS system generates very little grating lobes, but its power loss is not negligible. The other design of the microwave power transmitter is to use semi-conductor amplifiers. In this case, we could achieve a system with very small or no grating lobes. However, the efficiency of the semi-conductor amplifier is still below 40 % [4]and still much more expensive compared with the microwave tubes. Either system, therefore, does not attain sufficiently high DC-RF conversion efficiency. The higher the efficiency, the less launching weight and size can be attained. In this paper, we show a new concept of a microwave transmitter with phase controlled