Dual-Band Shared-Aperture High-Efficiency Reflectarray Antenna Based on Structure-Reuse Technique

A millimeter-wave dual-band shared-aperture high-efficiency reflectarray antenna (RA) based on the structure-reuse technique is proposed in this letter, which consists of two sets of elements with full 360° phase compensation ranges. The oblique dipole element excited by the substrate integrated waveguide (SIW) is employed for the lower frequency band. The equivalent metallic waveguide element with the unchanged periodic grid and transverse size is selected for the higher frequency band. To make full use of the radiating aperture and, then, improve the aperture efficiency of the dual-band RA, the SIW-fed dipole cells are used to replace a pair of symmetry walls of the metallic waveguide cell in the x-polarization direction. The measured gains of the proposed RA are 28.7 dBi with the aperture efficiency of 43.59% at 18 GHz and 35.8 dBi with the efficiency of 50.12% at 38 GHz. The simulated and measured results successfully validate the effectiveness of the proposed method in the design of a millimeter-wave dual-band shared-aperture RA.