Abstract
A novel shared-aperture reflectarray antenna (RA) based on structural multiplexing is proposed. Featuring mechanical reconfigurability, ultra-wideband performance is achieved, and manufacturing costs are significantly reduced. Through this design, the inherent bandwidth limitations of conventional shared-aperture reflectarrays are effectively overcome. RA2 and RA1 are passively reconfigured via a dual-layer structure to operate at 27.5–30.5 and 30.2–34.5 GHz, respectively. The reflection phase of each RA-unit is controlled by adjusting the dimensions of the square patches on the double-layer dielectric. Sidelobe levels are suppressed below −18.4 dB, with edge diffraction exerting minimal impact on the main radiation pattern. Experimental measurements confirm that a gain ranging from 27.2 to 28.0 dBi is achieved across the 27.5–34.5 GHz band, corresponding to a −1 dB gain bandwidth of 22.6%. An aperture efficiency exceeding 24% is maintained, reaching a peak of 39% at 28 GHz. The measured main beam remains relatively stable, with a 3 dB beamwidth of ∼5.3° in both the E- and H-planes.