Reflectarrays in Radio Telescope Design: a Preliminary Analysis

The antenna technology employed by radio astronomy has changed very slowly during the last few decades and thus an important question is whether novel antenna technologies might bring down the cost of collecting area for new facilities. In this work I discuss a few examples of application to the design of radio telescopes of a relatively new technology: reflectarrays. A reflectarray is a flat, planar, compact structure consisting of an array of isolated radiating elements which are predesigned with a particular phase delay to re-radiate and scatter the incident field to form a desired wavefront. Reflectarrays have become widely used for communications and radar applications, but so far there have been no proposals to use them in radio astronomy. Here, I will analyze the potential use of reflectarrays for radio astronomical applications, concentrating in particular on their ability to perform beam-scanning electronically.