Broadband, dual‐band reflectarray with dual orthogonal polarisation for single and multi‐beam patterns

Two single‐layered broadband dual‐band dual orthogonal polarisation reflectarrays are designed and developed in the X‐ and Ku‐bands. The well‐known holographic technique is employed such that one antenna generates a single radiation beam in two bands and another generates a five‐beam pattern in two bands simultaneously. For both antennas, a subwavelength Jerusalem‐Shaped unit cell is employed to independently realise two impedance distributions for each band and, consequently, not only broaden the operational bandwidths for both bands, but also limit the mutual coupling between two sets of impedances. As a typical case, an X/Ku band 20 cm × 20 cm five‐beam dual‐band reflectarray with dual linear polarisation is designed and fabricated for the experimental verification. The measurement results show that the fabricated antenna has 21% 1‐dB gain bandwidth (from 8.5 to 10.5 GHz) with vertical polarisation and has 8.8% 1‐dB gain bandwidth (from 14.65 to 16 GHz) with horizontal polarisation. Furthermore, the maximum measured aperture efficiencies in the X‐ and Ku‐bands are 57 and 69%, respectively.