A Dual Circularly-Polarized Multilayer Reflective Surface Based on Loaded Ring Slots

In this paper, a dual circularly-polarized multilayer reflective surface (MRS) based on loaded ring-slots for reflectarray applications is presented. The MRS comprises a wideband multilayer circular polarizer cascaded with a multilayer reflective screen with independent phase shifting properties for the two orthogonal linearly polarized components. The first polarization conversion is accomplished by a four-layer polarizer based on periodic arrays of bisected split rings that converts two incident circularly-polarized waves, one left-handed (LHCPW) and other right-handed (RHCPW), into two linearly polarized waves with orthogonal polarization planes. These two waves can be phase-shifted independently by a periodic two-layer array of specially designed reflective elements. Each element consists of a ring-slot resonator loaded with two pairs of reactances orthogonally located that can be varied to obtain two linear reflection phase tapers along the array. These reflected waves are then transformed back by the polarizer into two circularly polarized waves traveling into the desired directions. To validate the proposed approach, a six-layer prototype operating at 32 GHz that provides reflection elevation and azimuthal angles for the RHCPW at 22° and 180°, respectively, and reflection elevation and azimuthal angles for the LHCPW at 18° and 0°, respectively, has been designed, fabricated, and experimentally verified.