Realization of Quasi-Optical Output and Beam Deflection Based on Bifunctional Metasurface

On the demand of vacuum electronic devices, it is very important to realize high power beam quasi-optical and phase control. In this paper, a W-band bifunctional metasurface array is proposed as a mode convertor for gyrotron, which is based on the principle of propagation phase. The quasi-optical output of the metasurface is realized based on the rotation of the metasurface unit cell structure, which is based on the inverse process of the generation of radial vector field. On the other hand, the beam deflection can be realized based on the transmission phase principle and generalized Fresnel law. The beam deflection function of the metasurface array is verified by two beam deflection angles. The designed metasurface array has a good transmittance based on the simulation results, where the reflection S-parameter of the overall structure is less than −13 dB, and it has good performance with the bandwidth of 10 GHz. The proposed metasurface structure can realize quasi-optical, dual-function, and has the characteristics of miniaturization. The metasurface is expected to be used in microwave radar and satellite communication and this design method can also be applied to the THz band.