This report was prepared by the School of Electrical Engineering at Purdue University on Air Force Contract AF 33(616)- 7355 under Task Mo. 610.98 of Project No. 3145 "Microwave Energy Conversion".


MICROWAVE ENERGY CONVERSION Rectification by Semiconductor Diodes* A relatively simple method has been devised for mounting 680-1N830 diodes in a series parallel combination to form a single phase full-wave rectifier for operation at microwave frequencies. The efficiencies attained at 2440 Mc are as follows; Efficiency of 70% for 9 watts output, 65% for 18.7 watts, 55$ for 30.7 watts and 50% for 34 watts output.' Conversion by Bulk Semiconductor. An analytical study of bulk semiconductor conversion of microwave is presented. However, the material used for the experimental part of the project is not satisfactory for use at microwave frequencies. The polarization loss in this material reduces the efficiency from 50% to .05%. Other materials may be more suitable. Direct Rectification by Hot Cathode, (a) Four different tube mounts were tested and their efficiencies obtained. These efficiencies vary with load resistors, the maximum values lying between 21% and 25% for all set-ups and for resistors between 2000 and 4000 ohms.

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