Design aspects of the Microstrip reflectarray

The Microstrip reflectarray has been identified as one of the enabling technologies to achieve low mass, conformal mounting, wide-angle beam scanning, etc. [1] for NASA's future spaceborne high-gain antennas. It combines some of the best features of microstrip array antenna technology and the traditional parabolic reflector. Recently, the reflectarray antenna has found another horizon. It has the ability to integrate with the solar array and inflatable structures to achieve better overall system efficiency. There is a variety of types of printed reflectarrays. They are formed by basically using different elements, such as patches with variable phase delay lines [2,3] or variable rotation angles [4] and patches, rings, or dipoles with variable sizes [5,6,7]. These printed reflectarrays, although they are different, can be designed in a same fashion by using the simple conventional array technique [3]. Prior to the actual design, several important characteristics of the reflectarray, such as the element pattern, f/D ratio, bandwidth, feed pattern, etc., must be well understood by the designer in order to achieve a design with adequate efficiency.