Computationally Efficient Radiation Analysis of Beam-Steering Folded Reflectarray Antennas Using Plane-Wave Spectrum

This letter presents a numerical method for analyzing the radiation characteristics of beam-steering folded reflectarray (FRA) antennas. With the aid of the fast Fourier transform, near-field to near-field transformation between the two surfaces constituting the FRA antenna, as well as the computation of the co- and cross-polar far-field patterns and directivity, are performed computationally efficiently using the plane-wave spectrum. The proposed method was used to analyze a beam-steering FRA antenna with a $16{-}\lambda$ diameter ($\lambda$: wavelength). The radiation characteristics were computed in the order of milliseconds.