Nonreciprocal Nongyrotropic Magnetless Metasurface

TL;DR

This paper presents a lightweight, magnetless nonreciprocal metasurface that maintains polarization, uses transistor-based unidirectionality, and offers broad bandwidth and angular operation, advancing integrated nonreciprocal device design.

Contribution

It introduces a magnetless, nongyrotropic metasurface with a novel SCS architecture leveraging transistors for nonreciprocity, avoiding Faraday rotation and enabling integration.

Findings

Achieves nonreciprocity without magnets or Faraday rotation

Features broad bandwidth and angular sector operation

Is structurally equivalent to a moving uniaxial metasurface

Abstract

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.