EXPLORE THE FEASIBILITY OF AN ELECTRONICALLY CONTROLLABLE REFLECTIVE LENS TO FORM THE SUBREFLECTOR OF A DUAL REFLECTOR ANTENNA AND COMPENSATE ELECTRICALLY FOR MAIN REFLECTOR SURFACE DISTORTIONS.

EXPLORE THE FEASIBILITY OF AN ELECTRONICALLY CONTROLLABLE REFLECTIVE LENS TO FORM THE SUBREFLECTOR OF A DUAL REFLECTOR ANTENNA AND COMPENSATE ELECTRICALLY FOR MAIN REFLECTOR SURFACE DISTORTIONS. IT COULD ALSO PROVIDE LIMITED BUT EXTREMELY RAPID STEERING OF THE SECONDARY BEAM OF THE ANTENNA. SUCH A DEVICE WOULD BE USEFUL IN NUMEROUS SPACEBORNE AND GROUND BASED ANTENNAS, AND WILL BECOME MORE USEFUL AS FREQUENCIES AND ANTENNA SIZES CONTINUE TO INCREASE. THE LENS SURFACE WILL BE FORMED OF ELEMENTS SIMILAR TO THOSE USED IN FRQUENCY SELECTIVE SURFACES. ACTIVE ELECTRONIC CONTROL DEVICES, SUCH AS PIN DIODES OR FET'S, WILL BE ATTACHED TO THE ELEMENTS IN SUCH A WAY THAT ACTIVATION OF THE DEVICE ALTERS THE ELECTRICAL GEOMETRY OF THE REFLECTIVE ELEMENT, AND THEREFORE ALTERS THE RELATIVE PHASE OF THE REFLECTED ENERGY. CONTROLLING DIFFERENT AREAS OF THE SUBREFLECTOR INDEPENDENTLY PROVIDES BOTH COMPENSATIONFOR MAIN REFLECTOR SURFACE DISTORTIONS AND BEAM STEERING. PHASE I WORK WILL IDENTIFY THE BEST ELEMENT GEOMETRIES, CONTROL DEVICES, AND THEIR ARRANGEMENT TOGETHER INTO SINGLE OR MULTI-LAYER SURFACES TO FORM THE LENS. ANTENNA PERFORMANCE WILL E PREDICTED. PHASE II WILL VERIFY PERFORMANCE BY MEASUREMENTS.