  In this work, we develop a homogenization model to determine the effective
response of a metallic nanowire array embedded in an electric gyrotropic
material. We study the interaction of electromagnetic waves with the
metamaterial and demonstrate that the nanowire array can greatly enhance the
nonreciprocal response of the gyrotropic substrate. In particular, the
metamaterial can either absorb the incoming energy almost entirely or reflect
it with little loss, depending on the sign of the incidence angle. We explore
the implications of our findings in the context of Kirchhoff's law of thermal
radiation. Our results demonstrate that the wire array can boost the difference
between the emissivity and absorptivity in a broad spectrum of frequencies and
incidence angles as compared to an unstructured gyrotropic substrate. These
findings suggest potential applications for the nonreciprocal wire medium in
thermal management, radiative cooling, and others.
