Multiple beam bifocal reflector antenna design with front-fed offset Gregorian configuration

A multibeam bifocal reflector antenna (BFRA) design with a novel optical scheme in the symmetry plane is presented and discussed in this report. Reflectors arrangement looks like a known front-fed offset Cassegrain (FFOC) configuration; however associated caustic surface is located between sub and main reflectors. So, we call this arrangement a front-fed offset Gregorian (FFOG) configuration by analogy with FFOC. Antenna under consideration has aperture dimensions of 60 λ × 60 λ and was designed for required scan angle α = 10°. The feed is modeled as a simple point source with an axially symmetric radiation pattern. Achievable field of view (FoV) in the scanning horizontal plane is 28° for directivity > 44 dB and aperture efficiency (AE) higher than 55%. The FoV in the vertical plane is up to 6° for AE > 50%. Presented antenna is briefly compared with BFRA designs published earlier.