Retrodirective metasurfaces from non-reciprocal to reciprocal using impedance modulation for high-super-cell-periodicity designs

Abstract

The growing popularity of metasurfaces and their exceptional physical phenomena has gained remarkable interest in terms of propagation and electromagnetic wave control. Particularly, for the case of retroreflection, retrodirective gradient metasurfaces are well known for their reciprocal responses in terms of retroreflection specially for subwavelength super-cell periodicity designs. Recently, we have observed that for metasurfaces with high super-cell periodicities greater than $$2\lambda $$ , the retrodirective metasurface loses its reciprocal response in terms of retrodirectivity. The main challenge in this case is to retain the reciprocal response, as well as achieving efficient responses for retroreflection at the higher orders of diffraction that exist at these periodicities. Thus, in this paper we demonstrate the design of a retrodirective metasurface from non-reciprocal to reciprocal following the generalized phase law of reflection and introducing the impedance modulation technique, for a metasurface operating at 14.7 GHz with a super-cell periodicity of $$2.88 \lambda $$ . On the other hand, with a well-engineered surface impedance of a super-cell at these periodicities, efficient responses of retroreflection can be achieved at the higher orders of diffraction, giving rise to a retrodirective metasurface design operating simultaneously for multiple incident angles. Retroreflection has been achieved at eleven angles simultaneously, and the reciprocal property was retained at the desired angle of incidence $$10^{\circ }$$ .