A Hybrid Reflector Antenna for Two Contoured Beams With Different Shapes

A hybrid reflector antenna is presented in this letter to generate two contoured beams with different sizes and shapes using a single feed for each beam. This antenna is a dual offset Gregorian design with the Mizuguchi condition and is fed with two horns. One horn illuminates the main reflector and the other one illuminates the subreflector. In this antenna configuration, the main reflector aperture is shared by two contoured beams and the shapes of these two contoured beams are determined by main reflector surface and subreflector surface, respectively, and the electrical performances can be optimized independently. There is, therefore, minimal loss of gain in this dual coverage antenna as compared with a single/dual reflector dedicated to a single coverage. This method has many advantages such as providing two different shaped beams, good aperture efficiency, simple mechanical structure, light weight, and low complexity. The antenna design procedures are described in detail. The Ku-band Earth deck antenna prototype with dual shaped beams is designed, fabricated, and measured. A good gain performance is demonstrated for two different shaped regions. The difference between the predicted edge-of-coverage gain results and the measured results is less than 0.2 dB.