Conformal Cassegrain reflecting systems using meta-surfaces

Meta-surfaces have been applied into various conformal reflectors for the design of a Cassegrain system. In particular, we introduce different primary meta-surface reflectors of concave, planar, and convex profiles into the design of a dual reflecting system together with a secondary flat meta-mirror to generate highly directive beams. All these kinds of conformal Cassegrain reflecting systems are shown to possess aperture efficiencies comparable with conventional Cassegrain reflectors. While the concave meta-surface reflector offers the opportunity to build up a more compact system with a much smaller focal length, the planar meta-surface reflector demonstrates the characteristics of a low profile and easy fabrication, and the convex meta-surface reflector enables the whole system to be planted on a curved platform. Subwavelength square ring patches are finally employed to synthesize these reflectors and demonstrate their functionalities of tuning reflecting phases of electromagnetic beams with greatly enhanced radiation, both numerically and experimentally.