超宽角域广义布儒斯特超表面

Ultrawide-angle generalized Brewster metasurface

针对传统超表面存在大角度电磁性能恶化问题,提出了广义布儒斯特波阻抗匹配理论,实现超表面电磁性能的超宽角域稳定性.首先针对超宽角域透波问题,将超表面本征参数由各向同性标量推广至各向异性张量,建立包含入射角变量的各向异性超表面特性阻抗模型,推导了全角域透波的广义布儒斯特波阻抗匹配条件,将单一角度下的传统布儒斯特理论推广至整个角域.接着,针对电磁吸波问题,进一步将本征参数张量从实数域推广至复数域,建立了吸波超表面的复反射系数的角域模型,推导实现双极化超宽角域吸波的广义布儒斯特复波阻抗匹配条件,将广义布儒斯特波阻抗匹配理论由超宽角域透波推广至超宽角域吸波.最后,根据该理论分别研制了超宽角域透波和吸波超表面,仿真和实验均证明了它们在0?~80?超宽角域内的透波性能和在0?~75?超宽角域内的吸波性能.

A generalized Brewster impedance matching theory is proposed in this paper to overcome the performance degradation of conventional metasurfaces at large incidence angles and achieve ultrawide angular stability.To begin,in the case of transmission,the characteristic impedance of anisotropy metasurface,denoted by incidence angle and constitutive parameter tensor,is obtained by extending the constitutive parameter from the isotropy scalar to the anisotropy tensor.The theoretical formulas used to derive the generalized Brewster impedance matching condition extend the classical Brewster phenomenon to the entire angular domain.The constitutive parameters of the anisotropy metasurface are then extended to the complex domain for the case of absorption,and the complex reflection coefficient of the absorptive metasurface is established in the angular domain.To realize ultrawide-angle absorption,the generalized Brewster complex-impedance matching condition is derived,allowing the extension of ultrawide-angle transmission to absorption.Finally,ultrawide-angle transmissive and absorptive metasurfaces are designed,and their transmission of 0?–80?and absorption performance of 0?–75?are demonstrated using simulations and measurements.