Programmable Metamaterial for In-Plane Electromagnetic Wave Control in the Microwave Range

Tunable and programable devices hold a significant interest in electromagnetic (EM) engineering. A notable example is the programmable metasurfaces, which are quite powerful in controlling the phase front and steering beam of free-space waves. Similarly, managing in-plane EM waves on board is crucial for various applications. However, a programmable metamaterial (PMM) suitable for in-plane EM wave control is yet to be developed. Here, a PMM is presented that dynamically controls in-plane waves and is integrated on-boardly. The PMM is designed by incorporating metallic structures and tunable varactors. By biasing the varactors, a bulk module composed of an array of metamaterial unit cells can exhibit varied responses to incoming waves. As proof of concept, a PMM module for microwave control is fabricated and measured. In experiments, the PMM is successfully programmed to perform three distinct functions: wave splitting, Luneburg focusing, and wave differentiation, around the destination frequency (4.5 GHz). Although the PMM is dispersive and its bandwidth is somehow limited, its central frequency can be shifted in a dynamic range from 4 to 5 GHz. The proposed PMM resembles a miniaturized platform for reprogrammable in-plane wave control and manipulation, showing promise for realizing full wave operators, integrable computing, and deep learning devices.