Angular Momentum-biased metamaterials for filtering waveguide components and antennas with non-reciprocal behavior

In this contribution, we present a magnet-less non-reciprocal filtering module to be used in waveguide and antenna system for circular polarization applications. The filtering module, sandwiched between two thin dielectric slabs, consists of a annular aperture in a metallic screen which exhibits zero reflection, and thus maximum transmission, in a narrow frequency band around its resonant frequency. An artificial spatiotemporal modulation of the effective permittivity function around the annular aperture is introduced and, exploiting the concept of Angular Momentum-biased metamaterial, a non-reciprocity behavior takes place. The transmission and reflection coefficients turn out to be different for left- and right-handed circular polarized fields when impinging from the same side or, similarly, for the same polarization impinging from the opposite sides. Then, the non-reciprocal filtering module has been integrated in a circular waveguide and in an aperture antenna and we show some preliminary results of this new family of magnet-less non-reciprocal components.