Multibeam bifocal reflector antenna design with 40º field of view: A candidate for high gain ground station application

Abstract

This paper presents a design of Ku-band multiple beam offset dual-reflector bifocal reflector antenna (BFRA) with 40° field of view (FoV) that is suitable for high gain ground station applications. BFRA under consideration has a nearly square aperture with dimensions of about 4.5 m (191 wavelengths at a frequency of 12.75 GHz) and was designed for required scan angle α = 18° using a synthesis procedure proposed recently. Antenna has a Gregorian-like configuration in the offset vertical plane and a Cassegranian-like configuration in the scanning horizontal plane. A physical optics method is used to calculate the radiation patterns. In the case when maximum gain is needed, that is especially suitable for some receiving-only ground systems, the directivity of BFRA is higher than 53.8 dB and aperture efficiency is greater than 52% at a frequency of 12.75 GHz within the whole achievable FoV of 40° in the scanning horizontal plane. Such a BFRA design has FoV equal to 100 beamwidths and theoretically achievable minimum angular separation between adjacent beams of about 1°. Keywords-bifocal reflector antennas; multiple beam antennas; satellite ground stations; aperture efficiencyI.