A Broadband Reflectarray Antenna using the Triangular Array Configuration

A novel broadband reflectarray cell element is designed for use in several offset-fed reflectarray antennas based on square and triangular lattice. The proposed double-layer clement consists of two stacked rectangular patches having two slots in non-radiating edges. Reflection phase curves are obtained by changing simultaneously the slot's length of top and bottom patch. The designed element exhibits a large phase-shift range in excess of 360 degrees. This wideband cell clement is designed to be used in a triangular lattice that eliminates the grating lobes for wideband reflectarrays composed of unit-cell larger than half-wavelength. Two 529-element square reflectarrays and two 518-element triangular reflectarray antennas were designed and simulated using CST and HFSS, for producing 20 and 35 off-broadside E-plane beams using a 20 offset feed. The I-dB gain-bandwidth is about 30% at the center frequency of 14 GHz, and the maximum simulated gain is about 31 dBi which is equivalent to 51.5% aperture efficiency for a 20 degrees off-broadside reflectarray based on triangular lattice configurations.