Offset parabolic cylindrical antennas: effects of random surface errors on gain and sidelobes

The authors have developed a novel computational method for determining the average power pattern of an offset cylindrical parabolic reflector antenna subject to random surface errors. In particular, the computational results have been tailored for antenna dimensions similar to the one proposed for the space-borne precipitation radar mission. Both the boresight gain loss and sidelobe level degradations have been evaluated for various r.m.s. surface errors. It has been demonstrated that in order to keep the antenna sidelobe under the prescribed sidelobe template, one requires that the lower portion of the reflector surface maintains approximately /spl lambda//30 at Ka-band frequency and the rest of the surface maintain approximately /spl lambda//30 at Ku-band frequency. These results should provide useful guidelines for the overall design of the reflector surface and assist the proper selection of the required technology.