Topology optimization design of dual-channel metasurface structure with controllable amplitude of retroreflection and mirror reflection

For oblique incident electromagnetic waves, the generation of double reflection channels including retroreflection channel is of great significance to improve target recognition performance and navigation performance. In double channel reflection, controlling the proportion of retroreflection and specular reflection is the key to realize reflection power distribution. In order to realize the control of the proportion of the reflected power in each channel, a topology optimization method for designing the reflective metasurface microstructure with dual channel was proposed in this paper. The implementation mechanism and physical model of metasurface with dual reflection channel including retroreflection channel were constructed, and the topology optimization model of metasurface microstructure with specific power proportion of the retroreflection to specular reflection was established. As the numerical example, a dual channel metasurface reflector with a 1:1 ratio of retroreflection and specular reflection power was designed for a 10 GHz plane wave in the TE mode with -30 ° incident angle. The designed metasurface exhibited strong directionality in the retroreflective direction, and the reflection amplitude in both directions was similar. The retroreflective metasurface with the maximum retroreflection proportion was designed. The retroreflection proportion of the designed metasurface was 0.093. There was no specular reflection or other singular reflection, and the strong reflection on the metasurface was concentrated at -30 °. The ratio of the main beam power to the total reflection power was 0.900. The simulated and experimental results verified the feasibility of the proposed method.