Dual-Band Multiple Beam Reflector Antenna for Broadband Satellites

摘要

A broadband satellite antenna for producing a dual-band multiple beam coverage in transmission and reception based on an offset dual-optics configuration that includes a single main parabolic reflector, a hyperbolic sub-reflector, a first transmitting Multiple-Feed-per-Beam feed system, and a second receiving Multiple-Feed-per-Beam feed system. The sub-reflector surface is a Frequency Selective Surface configured to transmit any electromagnetic signals in the higher frequency band and to reflect any electromagnetic signals in the lower frequency band. The Multiple-Feed-per-Beam feed systems are located at the main focal point FMO and at the first sub-reflector real focal point FSreal. The eccentricity e of the hyperbolic sub-reflector depends on a ratio between a preset lower frequency fL in the lower frequency band BL and a preset higher frequency fH in the higher frequency band BH. The first transmitting Multiple-Feed-per-Beam feed system and the second receiving Multiple-Feed-per-Beam feed system are geometrical scaled versions of each other.

主权项

1. A broadband communication satellite antenna for producing a dual-band multiple beam coverage made of a transmit multiple beam coverage operating in a first transmitting frequency band BTx and a receive multiple beam coverage operating in a second receiving frequency band BRx, the first transmitting frequency band BTx and the second receiving frequency band BRx not overlapping, the communication satellite antenna being based on an offset dual-optics configuration and comprising:
a single main parabolic reflector having a main optical center O, a main focal point FMO and a main projected aperture diameter D, a sub-reflector, hyperbolic with a finite eccentricity e, that has a sub-reflector optical center FSO, a first sub-reflector real focal point FSreal and a second sub-reflector virtual focal point FSvirtual, a first transmitting Multiple-Feed-per-Beam feed system configured to generate the first transmit coverage and to illuminate the main reflector through the sub-reflector, and a second receiving Multiple-Feed-per-Beam feed system configured to generate the second receive coverage and to be illuminated by main reflector through the sub-reflector, wherein the sub-reflector is a Frequency Selective Surface configured to transmit any electromagnetic signals in the higher frequency band BH among the first transmitting and the second receiving frequency bands, and to reflect any electromagnetic signals in the lower frequency band BL among the first transmitting and the second receiving frequency bands, the sub-reflector optical center FSO is located between and aligned with the main reflector optical center O and the main reflector focal point FMO, the Multiple-Feed-per-Beam feed system among the first transmitting and second receiving Multiple-Feed-per-Beam feed systems that operates in the higher frequency band BH is located at the main focal point FMO, while the remaining Multiple-Feed-per-Beam feed system that operates in the lower frequency band is located at the first sub-reflector real focal point FSreal; the eccentricity e of the hyperbolic sub-reflector depends on a ratio between a preset lower frequency fL in the lower frequency band BL and a preset higher frequency fH in the higher frequency band BH, and is determined according to the implicit equation:fHfL=e2-1(e2+1)-2ecosβ, where β is a predetermined tilt angle between the axe of symmetry of the parabola defined by the main reflector and the axe of symmetry of the hyperbola defined by the sub-reflector; and the first transmitting Multiple-Feed-per-Beam feed system and the second receiving Multiple-Feed-per-Beam feed system are geometrical scaled versions of each other.