Modulated Frequency-Selective Doubly Curved Sub-Reflector for a Dual-Band Multiple Spot Beam Communication Satellite Antenna System

An antenna solution for broadband communication satellite applications is presented. The proposed antenna design provides a full dual-band (Tx/Rx) four-color multibeam coverage of Europe in K/Ka-band while utilizing only a single main reflector aperture. This solution is especially relevant for smaller platforms and secondary payloads. The antenna system consists of an offset Cassegrain antenna combining two multiple-feed-per-beam (MFB) feed clusters and a doubly curved modulated frequency-selective surface (FSS) sub-reflector, which is the key enabling technology validated in this work. By utilizing a modulated FSS design, the antenna system fulfills all radio frequency (RF) requirements that were specified on the antenna coverage parameters. An engineering model (EM) of the doubly curved FSS sub-reflector has been designed and fabricated. Its RF performance was characterized experimentally, and good agreement has been observed between simulations and measurements, thus validating the proposed concept.