Single polarization reflectarray design based on an element with seven parallel dipoles to generate independent beams in three frequency bands

Abstract

A single layer reflectarray element based on seven parallel dipoles is proposed for single polarization applications. The dipoles of the reflectarray element make it possible a multi-resonant behavior which provides very large phase range, while keeping low loss and low cross-polarization level. A sequential design process of a reflectarray antenna is proposed where the lengths of the dipoles are adjusted in pairs to provide the required phases which generate three independents beams at 20, 25 and 30 GHz. The simulated radiation patterns of the reflectarray antenna exhibit efficiencies of 80%, 62% and 52% at 20, 25 and 30 GHz respectively. The maximum cross-polar radiation obtained is 29.7 dB, 32.9 dB and 39.1 dB below the maximum of the co-polar beam at 20, 25 and 30 GHz respectively. Bandwidths of 14%, 8.2% and 4.3% are achieved at center frequencies of 20, 25 and 30 GHz respectively. These bandwidth results account for a +/-0.5° of deviation in the main beam direction, for 2dB-gain variations in the two first bands, and for a 3dB gain variation in the last band.