Passive Dual-Band Shared-Aperture Reflective Metasurface with Large Frequency Ratio for Sub-6 GHz/mmWave Band Communication

This paper introduces a passive dual-band single-layer reflective metasurface featuring a large frequency ratio of 8 for the first time. The metasurface includes two types of 28 GHz elements and two types of 3.5 GHz elements, all exhibiting stable performance across various oblique incidence angles. The elements exhibit phase shift ranges surpassing 300 degrees amid minimal reflection losses less than 1.38 dB. The measured peak gain for the prototype, consisting of 24 x 24 28 GHz elements and 14 x 14 3.5 GHz elements, are 23.3 dBi with a sidelobe level (SLL) of -14.2 dBi at 28 GHz and 17.8 dBi with SLL of -12.4 dBi at 3.5 GHz respectively. This design marks a promising starting point for single-aperture dual-band reflective metasurface applications in microwave/millimeter wave spectrum.