Three-Dimensional-Printed Wideband Perforated Dielectric-Only Reflectarray in Ka-Band

In this article, a dielectric-only reflectarray (RA) with a wideband behavior is proposed as an alternative to conventional metallo-dielectric configurations. The introduced unit-cell (UC) consists of a single dielectric layer perforated with a square hole located at the center, whose size is used to control the phase of the reflection coefficient. For such a dielectric element, an accurate equivalent circuit model for predicting the reflection coefficient is derived by combining two different concepts: the effective medium theory used to characterize the effective permittivity and the Floquet modal expansion to describe the wave propagation in terms of Floquet modes. The UC geometrical parameters are then optimized to maximize the RA performance, taking also into account the limitations introduced by the additive manufacturing (AM) process adopted for the realization of a prototype. Its experimental characterization confirms the effectiveness of the UC, of the design and manufacturing procedures: in fact, the measurements, in very good agreement with the results of the simulations, prove the significantly low sidelobe levels, the good aperture efficiency, and the excellent 1-dB bandwidth (BW), larger than 24%.