limit for the permissible microwave power density which can be sent through the ionosphere. The number being used, 23 mW/cm2 is based on an obsolete theoretical foundation and is without experimental support, and yet it is the constraining parameter in a number of the SPS design areas. Sufficient funds and resources should be allocated so that this question can be answered as soon as possible. There should be more emphasis on systems engineering in the SPS and MPTS design. Sensitivity trades should be employed more frequently to reveal optimum design parameters and directions. Design decisions made early in the program do not appear to have been subject to continued scrutiny and review. Updating the design approaches, and major reviews of the overall concept should be done on a frequent basis. A systems level failure analysis should be done. There should be some effort expended towards insuring that the entire system will fail gracefully, and not in a catastrophic manner. Detailed design work has gotten ahead of systems level planning in some areas. The design philosophy appears to be based solely on optimizing the efficiency of each individual component of the system. There needs to be more emphasis on evaluating the cost sensitivity of the design, with the possibility of achieving a slightly less efficient system that is considerably less expensive. One area in which this is particularly true is the rectenna. A lower cost rectenna, if it could be achieved, might allow one satellite to use widely separated rectennas, with the beam shifting from one to the other as the peak load shifts. It would be useful to attempt to feed innovative or novel ideas into the design concept from time to time, rather than trying always to refine the original reference design. The panel feels that some of the major electronics and communications companies should become involved in the MPTS design since some of the design concepts do not appear to be up to contemporary standards for equivalent military systems. The panel feels that any experimental work at this stage of the SPS systems development should be very carefully thought out. In some instances, some hard data is needed now, before further planning can be undertaken. Breadboarding a particular system, however, just to demonstrate a concept, does not seem warranted until further systems review has been accomplished. Microwave systems are critically dependent on the precise configuration and components which are used in their construction. Building a system in the laboratory which will look nothing like the deployed system will not yield much useful information and is probably a waste of resources. The problem with rf interference from the MPTS looks to the panel to be severe and not adequately addressed at this time. Not only are the noise sidebands from the transmitter uncomfortably close to the maximum limits set by the radio astronomers, but the harmonic radiation from both the SPS itself, as well as reradiation from the rectenna look particularly bothersome. At the power levels envisioned with this concept, intermodulation products between harmonics and many other rf sources will be a major concern. There does not appear to be enough emphasis at the systems planning level for controlling the harmonic generation and radiation problem. It was apparent from the workshop presentation that not enough attention has been paid to the problem of security and anti-jamming. State-of-the-art cryptography and NSA security standards should be built into the system design from the outset. Coordination with appropriate agencies should begin now so that a smooth integration of their requirements into the SPS system can be achieved. Finally, the panel feels that the project organization and structure could be im-
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