ACTIVE PROGRAMMABLE MICROWAVE DIRECTIONAL COUPLER

PHASED ARRAY RECIEVERS AND TRANSMITTERS, IT IS OFTEN NECESSARY TO IMPLEMENT A METHOD OF INDEPENDENTLY CONTROLLING THE AMPLITUDE OF THE SIGNAL RECEIVED FROM OR TRANSMITTED TO EACH ELEMENT. IN PRACTICAL TERMS, THIS REQUIREMENT MAY BE SATISFIED BY A DIRECTIONAL COUPLER WITH A VARIABLE COUPLING RATIO. FOR APPLICATIONS IN MODERN MULTI-FUNCTION ARRAY, THE COUPLER DESIGN IS ADDRESSED TO THE NEED TO DEVELOP AN MMIC PROGRAMMABLEDIRECTIONAL COUPLER. SOME PRELIMINARY ANALYSES OF A POSSIBLE COUPLER DESIGN ARE PRESENTED TO SHOW THE EXPECTED PERFORMANCE CHARACTERISTICS. A METHOD OF CONTROLLING THE GAIN OF A COUPLED OUTPUT USING SEGMENTED DUAL-GATE FETS IS ALSO PRESENTED. WITH THIS APPROACH, AMPLITUDE CONTROL OF OVER 30 DB IS PREDICTED WITH NEGLIGABLE PHASE DISTORTION. THE PROPOSED PROGRAM PLAN INCLUDES A STUDY OF ALTERNATE DESIGN APPROACHES AND COMPLETE ANALYSIS AND DESIGN/LAYOUT OF THE SELECTED CIRCUIT TOPOLOGY, WHICH IS FULLY COMPATIBLE WITH MMIC-BASED ACTIVE T/R MODULES