3-d printed all-dielectric dual-band broadband reflectarray with a large frequency ratio

This communication proposes a new all-dielectric broadband dual-band reflectarray with a large frequency ratio using low-cost 3-D printing. In contrast to conventional reflectarrays using metallic resonant cells or dielectric slabs as phasing elements with full metal ground, the proposed design uses air as the phasing element and a stepped dielectric mirror structure as the ground. In this way, the metal ground is removed, which makes the design an all-dielectric one. Taking advantage of the dielectric mirror that only exhibits a bandgap in the predesigned band while allowing electromagnetic (EM) waves to pass through it at the frequency out of the bandgap region, a dual-band reflectarray is obtained. By properly selecting the bandgap frequency of the dielectric mirror, the dual-band frequency ratio is scalable and can be very large. Furthermore, instead of using a metallic or dielectric resonator based on resonance, air layers with linear phase response are adopted as the phasing element. Thus, the reflectarray shows broadband and stable performance over the dual-band. Compared with the state-of-the-art works using printed circuit boards (PCBs) or microfabrication, the proposed design is low cost and lightweight, and can be rapidly prototyped. For proof-of-concept, a prototype operating at K -band and V -band with a frequency ratio of 2.7 is printed and measured.