# Nonreciprocal Phase Gradient Metasurface: Principle and Transistor Implementation

## TL;DR

This paper presents a novel nonreciprocal phase gradient metasurface based on bianisotropic unit cells, featuring a transistor implementation, and demonstrates its application in a simulated 6-port spatial circulator.

## Contribution

It introduces the concept of nonreciprocal nongyrotropic metasurfaces and provides a transistor-based design for nonreciprocal phase shifting units.

## Key findings

- Successful simulation of a 6-port spatial circulator
- Design of a transistor-based nonreciprocal phase shifter
- Validation of nonreciprocal phase gradient metasurface concept

## Abstract

We introduce the concept of nonreciprocal nongyrotropic phase gradient metasurfaces. Such metasurfaces are based on bianisotropic phase shifting unit cells, with the required nonreciprocal and nongyrotropic characteristics. Moreover, we present a transistor-based implementation of a nonreciprocal phase shifting subwavelength unit cell. Finally, we demonstrate the concept with a simulation of a 6-port spatial circulator application.