SRC-558

Electronic and Mechanical Improvement of the Receiving Terminal of a Free-Space Microwave Power Transmission System -- NASA CR-135194; Raytheon report PT-4964; August 1, 1977

Commissioned by NASA Lewis Research Center, Contract NAS3-19722; two NASA Lewis programme managers named on the report documentation page. Who paid for a study is recorded because it bears on how its conclusions should be read, not because it makes them wrong.

Published claims resting on this source

• CLM-1095 The three harmonic numbers the register has carried since the 1978 conference paper come from one rectenna element on a bench at five watts, measured at its input with the antenna replaced by a matched line; the fourth is the meter's floor, not a reading. Filters and a metal shield on the element cut the second and third by 25 and 15 decibels.
• CLM-1096 In 1977 one rectenna element converted 90 per cent of eight watts of microwaves to DC but only 80 per cent of fifty milliwatts, and the report says why: at low power the diode's own losses dominate. The 85 per cent the programme wanted at low power was not reached.
• CLM-1097 By 1976 a rectenna had delivered thirty kilowatts over a mile at 82 per cent, a certified bench system had turned DC into microwaves and back at 54 per cent, and 199 elements had run four months without a failure, which the maker converted into a 27-year mean time between failures at 90 per cent confidence.
• CLM-1098 The 1977 plan for a cheap rectenna was two flat planes, the front one doing all the work inside a metal shroud that is also the structure, wired in series to reach a thousand volts for the inverters; a five-element piece was built and worked, and the report says the next thing to build is a thousand-volt section.

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