PO optimized dual-offset reflector antenna with subreflector scan mechanism

A dual-offset reflector limb sounding antenna is described where the beam scan is provided by a linear displacement of the subreflector. This technique yields the advantage of a very low mass to be moved. The numerical design method which is immediately based on the physical optics (PO) procedure achieves improved scan performance without severe pattern problems by adequately shaping both reflectors. The method involves an evolution strategy optimization algorithm where both the subreflector and main reflector surfaces are characterized in the spatial domain in order to reduce the optimization parameters significantly. The example of a shaped dual-offset 200 GHz elliptical Cassegrain reflector antenna with nearly constant half-power beamwidth as a function of the scan angle demonstrates the efficiency of the design method.<>