CHARACTERIZATION OF GAAS IMPATT DIODES FOR ACTIVE APERTURE APPLICATIONS

UNDER A PREVIOUS AFWAL CONTRACT, AND UNDER INTERNAL SPONSORSHIP, LNR COMMUNICATIONS, INC. HAS DEVELOPED FOR ULTIMATE SPACEBORNE DOWNLINK USAGE AND DEMONSTRATED BRASSBOARD 10W AND 20W, 20GHZ IMPATT SOLID STATE POWER AMPLIFIERS (SSPA'S) WITH 1GHZ BANDWIDTH AND IN 4 AND 8WAY COMBINATORIAL CONFIGURATIONS, RESPECTIVELY. EACH OF THESE SSPA'S UTILIZE A MULTIPLICITY OF IDENTICAL 2.5W IMPATT AMPLIFIER "BUILDING BLOCKS" IN A BINARY CORPORATE COMBINATIONAL CONFIGURATION INCORPORTING A LOW LOSS OUTPUT POWER COMBINER. BY VIRTUE OF THE FOREGOING TOPOLOGY, THIS SSPA DESIGN (OR ITS 16,32,...WAY COUNTERPARTS, CAN BE ADAPTED TO ACTIVE-APERTURE "PHASED ARRAY" TRANSMIT ANTENNA USAGE BY REPLACING THE OUTPUT POWER COMBINER WITH A MULTIPLE-RADIATING ELEMENT ANTENNA FEED ARRAY. ACCORDINGLY, IT IS THE PURPOSE OF THIS STUDY TO THEORETICALLY AND, WHERE POSSIBLE, EXPERIMENTALLY, INVESTIGATE THE SUITABILITY OF SUCH IMPATT "BUILDING BLOCKS" FOR SPATIALLY COMBINED ACTIVE APERTURE 20GHZ SATCOM DOWNLINK TRANSMITTER USAGE UNDER TYPICAL SPACECRAFT/ENVIRONMENTAL AND ACTIVE APERTURE SYSTEM DESIGN CONSTRAINTS. THE PROPOSED STUDY WILL CULMINATE IN A FINAL REPORT PRESENTING AN OPTIMIZED 20 GHZ SPATIALLY COMBINED IMPATT ACTIVE APERTURE SSPA DESIGN APPLICABLE TO THE SUBSEQUENT IMPLEMENTATION OF A BRASSBOARD FEASIBILITY MODEL.