Transmit-Receive Parabolic Reflectarray to Generate Two Beams per Feed for Multi-Spot Satellite Antennas in Ka-Band

Abstract

This article describes the design of a multibeam parabolic reflectarray to produce two adjacent beams per feed in orthogonal Circular Polarization (CP) simultaneously at transmit(Tx) and receive (Rx) frequencies in Ka-band. The Variable Rotation Technique (VRT) has been applied to reflectarray cells based on two types of resonant elements, which makes it possible to provide orthogonal beams at Tx and Rx, as well as to implement an in-band optimization procedure to reduce the cross-polarization. A 90-cm parabolic reflectarray has been designed, manufactured and tested to produce multiple adjacent beams in RHCP and LHCP at both 20 and 30 GHz. The results are satisfactory and validate the concept of generating two spaced beams in orthogonal CP by a single feed, changing the polarization of the beam between Tx and Rx. This concept can be suitable for multispot satellites in Ka-band, enabling to halve the number of onboard antennas and feeds.