The economic issue is a serious one and I believe it is this issue that has largely and properly motivated the current SSP study, whose first phase has been largely devoted to taking a look at other architectures that might be more economical in the long ran, and/or could provide a less costly initial phase of development than the architecture that the DOE/NASA study in 1977-1980 produced. The author has reviewed these alternative approaches and it is his opinion that no alternative approaches have yet been identified that are clearly superior in their long term development to the existing approach and certainty no alternative approach is nearly as far advanced, engineering wise, as is the existing one. In any event, the high cost of transportation into space precludes any immediate development of the Solar Power Satellite. Therefore, it would be easy to conclude that there is no good reason to go forward with any development work of any nature on the SPS. However, in the affairs of mankind the unexpected event that needs a technical solution sometimes happens and it becomes necessary to go with the most ready technology at the moment. If wireless power transmission were the technology needed, not necessarily for the SPS but for some other application, certainty the technology at 2.45 gigahertz is the furthest developed in both the transmission and the reception portions of the system, and is the least sensitive to conditions in the Earth’s atmosphere. It would therefore seem logical to give demonstrations of the capability of the existing technology to perform new functions and to refine and improve certain critical areas of the existing technology. Recommended Program of Demonstration and Technology Refinement My observation and recommendation, therefore, is that we should take action in two specific areas. One is to demonstrate an electronically steerable phased array with existing hardware, with two purposes in mind. One of the purposes, particularly if it is done under an experimental license, is to encourage the NTIA (National Telecommunications Information Agency) to take action to preserve the 2.45 GHz frequency for power beaming purposes. The second purpose is to just demonstrate the ability of present low cost technology to perform the electronic steering function which will be required in the SPS transmitter. The other specific area is an attempt to remove the present inability of the magnetron to operate with low noise at the very high efficiencies, 85% to 90%, required for the SPS transmitter. Otherwise, the magnetron has the unique capability, among all other candidate microwave generators, of simultaneously meeting a host of other requirements imposed on the microwave generator that will be the subject of further discussion later in this paper. Fortunately, it is possible to be quite specific about the action that should be taken in these two areas of demonstration and technology refinement Experimental Demonstration of an Electronically Steerable Array with SSP Technology The experimental action that the author believes should be taken is based upon the work on the ESPAM (Electronically Steerable Phased Array Module) that has been sponsored by the Center for Space Power at Texas A&M University. This work has been reported upon by the writer in reference [1], and will be made available to any one interested. Essentially, the ESPAM is a module composed of a small section of slotted waveguide antenna driven by an MDA (Magnetron Directional Amplifier). In turn the MDA is a conventional magnetron converted with external circuitry into a phase-locked, high-gain amplifier. The ESPAM now exists in a hardware form suitable for use in a ground based, electronically steerable phased
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