Arbitrarily-shaped-beam microstrip reflectarray based on phase-retrieval method

For shaping a beam of millimeter-wave reflectarrays arbitrarily, this paper proposes a directivity synthesis based on the algorithm of the phase-retrieval method. The unknown phase distribution is numerically determined from an illumination distribution on the aperture and a desired beam pattern by iterative approach. As a design example, we present an elliptical-beam microstrip reflectarray with an offset feed. The effectiveness of the proposed reflectarray is verified by the near-field antenna measurements at 45 GHz.