Bandwidth Behavior of Closely Spaced Aperture-Coupled Reflectarrays

The bandwidth features of reflectarray antennas are analyzed by examining in detail the phase errors due to the compensation mechanism for spatial phase delays. A bandwidth estimation rule is defined, taking into account the combined effects due to the overall antenna geometry and the frequency response of the single reflectarray element. An aperture-coupled reflectarray configuration with reduced interelement spacing is considered as broadband solution for the implementation of small reflectarrays. A 20 GHz aperture-coupled element is synthesized for the design of a 12 diameter reflectarray, showing a simulated 1 dB gain bandwidth of 23%