THERMALLY COOLED SPACECRAFT LOW NOISE AMPLIFIER DESIGN STUDY

A NEED EXISTS FOR SPACE QUALIFIED EHF LOW NOISE RECEIVER FRONT-ENDS OPERATING AT FREQUENCIES OF 44 GHZ AND UP. RECENT ADVANCES IN THE AREA OF HEMT DEVICE TECHNOLOGY MAKE IT POSSIBLE TO DEVELOP A SPACE QUALIFIABLE LOW NOISE AMPLIFIER WITH GAIN AND NOISE FIGURE PERFORMANCE APPROACHING THAT PREVIOUSLY AVAILABLE ONLY WITH PARAMETRIC AMPLIFIERS. TO ACHIEVE THESE NOISE PERFORMANCE LEVELS IT IS HOWEVER NECESSARY TO COOL THE HEMT DEVICE THEREBY REDUCING ITS THERMAL NOISE CONTRIBUTION. ACCORDINGLY, THE PROPOSED PHASE I PROGRAM ENTAILS THE PERFORMANCE OF A DESIGN STUDY TRADEOFF ANALYSIS CULMINATING IN THE GENERATION OF A PREFERRED DESIGN APPROACH FOR A SIMPLE, LIGHTWEIGHT, LOW COST HEMT LNA AT 44 GHZ WITH NOISE FIGURE AND GAIN OF 3-4 DB AND 10-15 DB RESPECTIVELY. ESPECIALLY THE STUDY WILL CONCENTRATE ON FIVE TECHNOLOGICAL AREAS TRADING OFF ELECTRICAL, THERMAL AND MECHANICAL DESIGN PRINCIPLES TO ACHIEVE MAXIMUM NOISE PERFORMANCE. AREAS TO BE INVESTIGATED ARE: 1) HEMT DEVICE TECHNOLOGY STATUS, 2) ACTIVE COOLING METHODS, 3) RF CIRCUIT DESIGN, 4) THERMAL TRANSFER/MECHANICAL STRUCTURE AND 5) SPACECRAFT INTERFACE. THE COOLED LNA DESIGN CONCEPTS, SO GENERATED, WILL ALTHOUGH FOCUSED AT 44 GHZ BE DIRECTLY TRANSFERABLE TO OTHER EHF FREQUENCIES OF OPERATION.