Dual-Band Shared-Aperture Reflective Surface Featuring Wide Band-Ratio Across Sub-6 GHz and Millimeter-Wave on a Single-Layer

This communication demonstrates a passive reflective surface (RS) capable of independently generating beams at both sub-6 GHz and millimeter-wave (mmWave) bands using only a single-layer substrate for the first time to be reported in the literature. Independent phase shift at both bands can be achieved within a shared aperture through a unique combination of concentric annular loop elements and open-ended stubs. This is further supported by the utilization of double-ringed circular elements, which suppress mutual interference between the two bands, while conventional cross-dipole elements are employed for structural brevity. Through full-wave simulations, it is numerically verified that the proposed RS exhibits excellent radiation performance, independently supporting reflected beam angles of up to 60° at each band. Furthermore, experimental validation of this performance is provided through far-field measurement results obtained from the fabricated RS prototype. Due to the wide frequency ratio of 8 and the simple structure of the RS, this design is expected to be beneficial for more efficient coverage enhancement of future generation (5G and 6G) wireless networks encompassing sub-6 GHz and mmWave spectrums.