Design of a UWB Reflectarray as an Impedance Surface Using Bessel Filters

This paper develops a framework for designing wideband reflectarray antennas. The proposed reflectarray is implemented as a scalar impedance surface composed of subwavelength elements, whose response is designed to realize a Bessel filter response. The underlying unit cells therefore have maximum group delay bandwidth with no group delay ripples in the passband. It is shown that the reflectarrays designed using this Bessel filter approach exhibit wide bandwidth only limited by the order of the filter used to realize the Bessel filter. Simulated and measured antenna characteristics of the proposed reflectarray are presented for a C-/X-band reflectarray design. It is shown to have good beam characteristics and ultra-low temporal dispersion from 5 to 10 GHz, two attractive qualities accomplished simultaneously by the proposed reflectarray.