System study and technical development on the Solar Power Satellite with concentrators and transmitters in the sandwich structure

太阳能发电卫星（SPS）是一种独特的、有希望的发电站，可以在不破坏地球母亲环境的情况下满足地球上日益增长的能源需求。然而，由于DOE/NASA设计的参考系统过于庞大和昂贵，必须在SPS上寻求新的突破。我们已经提出了一种新的SPS概念，它由一个夹层结构的发电机/发射机和大型集热器组成。为了实现SPS的新概念，我们正在开发一种新型的高功率微波发射机，该发射机在夹层结构中加入了反向定向天线。对新型微波发射机进行了如下改进：1)更高的频率可以使发射机体积更小。微波的频率为4.8 GHz，使发射机的直径减小一半。2)利用微波的半频（2.4 GHz）作为反向定向天线的导频信号，使射频电路非常简单和精确。4)发射天线直接与放大器相连，减少电缆损耗，减轻天线重量。我们成功地利用反向定向天线进行了微波功率传输演示，以实现精确的波束控制。

The Solar Power Satellite (SPS) is one of the unique and hopeful electric power stations to satisfy ever-increasing energy demand on the ground without destroying the environment of our mother planet Earth. However, new breakthroughs must be investigated on the SPS, because the reference system designed by DOE/NASA is too huge and too expensive for the realization. We have already proposed a new concept of the SPS, which consists of a generator/transmitter of a sandwich structure and large collectors. We are developing a new high power microwave transmitter with a retrodirective antenna in the sandwich structure in order to realize our new concept of the SPS. The new microwave transmitter has successfully been improved as follows :1)Higher frequency can make the transmitter smaller. The frequency of the microwave is 4.8 GHz to make the diameter of the transmitter half.2)Half frequency (2.4 GHz) of the microwaves is used as a pilot signal of the retrodirective antenna to make RF circuit very simple and accurate.4)The transmitting antenna is directly connected to the amplifiers to reduce the loss of cables and the weight of the antenna.We successfully carried out a Microwave Power Transmission demonstration using the retrodirective antenna for the accurate beam control.