Bifocal Single Reflectarrays with Application to Multibeam Satellite Antennas

In the last decades, reflectarrays have emerged as a new generation of high-gain antennas, combining many favorable features of both reflectors and arrays, as well as offering an alternative design with low-profile and low-mass features. The aperture of a reflectarray antenna consists of sub-wavelength elements arranged in a certain grid that are typically designed to collimate the main beam of the antenna by controlling the phase of the reflected wave. Reflectarray antennas are characterized by appealing features, particularly a low weight and low profile, which are ideally suited for space applications, combined with ease of manufacturing, good efficiency, and high gain. A prominent advantage of reflectarrays over reflectors is the possibility to obtain direct phase control over every element on the aperture. This feature can be exploited to improve scanning performances at no additional cost and without the distribution losses associated with the feed network for large array antennas. Recently, the potential of reflectarrays for the design of advanced multibeam antennas has been investigated [E. Martinez-de-Rioja et al., “Advanced Multibeam Antenna Configurations Based on Reflectarrays: Providing multispot coverage with a smaller number of apertures for satellite communications in the K and Ka bands,” in IEEE Antennas and Propagation Magazine, vol. 61, no. 5, pp. 77–86, Oct. 2019.]