All-passive microwave-diode nonreciprocal metasurface

Abstract

Abstract Breaking reciprocity in the microwave frequency range is strongly desirable in the development of modern electronic systems, as it enables nonreciprocal wave absorbing, nonreciprocal beam steering, frequency conversion, and protection of sensitive devices from high energy sources. However, the typical approaches involve bulky biasing magnets or complex spatial-temporal modulations. As such, resorting to lightweight and all-passive platforms would result in optimal configurations and efficient integration. Starting from a circuit model, we theoretically demonstrate the nonreciprocal behavior on a transmission line building block creating a strong field asymmetry with a switchable matching stub to enable two distinct working states. After translating to an electromagnetic model, this concept is first proved by simulation and then experimentally verified on a microstrip-line-based diode-integrated metasurface showing nonreciprocal transmission. This printed circuit board design is expected to find various applications in electromagnetic protecting layers, communication systems, microwave isolators and circulators.