  We introduce a nonreciprocal nongyrotropic magnetless metasurface. In
contrast to previous nonreciprocal structures, this metasurface does not
require a biasing magnet, and is therefore lightweight and amenable to
integrated circuit fabrication. Moreover, it does not induce Faraday rotation,
and hence does not alter the polarization of waves, which is a desirable
feature in many nonreciprocal devices. The metasurface is designed according to
a Surface-Circuit-Surface (SCS) architecture and leverages the inherent
unidirectionality of transistors for breaking time reversal symmetry.
Interesting features include transmission gain as well as broad operating
bandwidth and angular sector operation. It is finally shown that the
metasurface is bianisotropic in nature, with nonreciprocity due to the
electric-magnetic coupling parameters, and structurally equivalent to a moving
uniaxial metasurface.
