A Broadband Reflectarray Antenna Using Single-Layer Rectangular Patches Embedded With Inverted L-Shaped Slots

A novel single-layer element consisting of a rectangular patch embedded with a pair of inverted L-shaped slots is proposed for broadband reflectarray antennas. The dimensions of rectangular patch for all elements are identical, and the phase variation is achieved by adjusting the length of the etched slots within the patches. By this means, the abrupt geometry changes for adjacent elements in traditional reflectarrays can be avoided. The unit cell is optimized to offer a linear phase response with sufficient phase variation range. Based on the proposed element, a 529-element offset-fed reflectarray centered at 10 GHz with 0.3\lambda grid spacing is designed and constructed. Different from conventional element arrangement for reflectarrays, a special element layout is adopted in this paper to significantly reduce the cross-polarization (cross-pol) level. The measurement results show that a broad 1 dB gain bandwidth of 23% is obtained, with an aperture efficiency of 67% and a cross-pol level of 26 dB at 10 GHz.