Non-reciprocal electromagnetic wave transmission enabled by space-time-encoded digitally-induced magnetic Huygens’ metasurfaces

Abstract

Non-reciprocal electromagnetic wave transmission is crucial for applications like antenna radomes and full-duplex systems. Space-time coded metasurfaces introduce temporal modulation to enhance device reconfigurability and design flexibility, offering a promising pathway for achieving non-reciprocal wave manipulation. However, existing reflective space–time–coded metasurfaces suffer from the inherent drawback of feed blockage, whereas transmissive designs, while avoiding such issues, face higher complexity in design and implementation. To address this challenge, we propose a transmission-type space-time coded digital induced magnetic Huygens’ metasurface composed of anti-symmetric parallel metallic split-ring resonators integrated with varactor diodes. By independently controlling the varactor diode via an FPGA module and employing a precisely designed 2-bit space-time coding sequence, control over non-reciprocal transmission in a transmissive metasurface is successfully achieved. Results validate the effectiveness and accuracy of the proposed scheme, providing new insights for advancing space-time coded metasurfaces and developing novel non-reciprocal transmission technologies.