Experimental research and design of microwave power transmission system for SSPS application

Microwave power transmission (MPT) is the core technology of the Space Solar Power Satellite (SSPS). Experimental research and design of a MPT system considering the proposed limit for the center-of-beam power densities to assure environmental health and safety for microwave transmission was presented in this paper. Under the power density limit, an experimental system with solid power amplifier at 5.8 GHz was constructed and tested. In addition, to solve the problem of efficiency decline because of impedance mismatch in different interface between antenna output and rectifier circuit input, meanwhile to block harmonic re-radiation caused by nonlinearity of rectifier circuit, rectifying surface was researched based on sub-wavelength element in rectenna. By changing structure conjugated match between antenna output impedance and rectifier circuit input impedance, the rectifying surface exhibits a strong restrain to high-order harmonics and eliminating the need for RF filter which is an important element for the traditional rectenna, so the circuit structure is simple and high conversion efficiency can realize. In experiment, the measured maximum conversion efficiency of RF to DC is 57.7 %. The results show that the designed microwave power transmission system is benefit for ground demonstration testing in miniature version and building of SSPS in future.