An anisotropic unit cell based on glide symmetry is proposed for tailoring a metasurface that engineers an optically transformed Luneburg lens. Thanks to the optical transformation, the size of the lens is reduced by 25%. The proposed lens is ultrawideband, and it covers multi-octave frequency bands. The required constitutive materials are achieved in an air gap bounded by top and bottom glide-symmetric metasurfaces; i.e., they are off-shifted by half the period. Each surface is implemented in standard printed-circuit-board technology, and its unit cell consists of a grounded substrate with an elliptical holey top cladding surrounded by metalized through-vias. This technology, known as substrate-integrated-holes (SIHs), mimics the operation of holes drilled in a parallel plate but provides the higher effective refractive index required for lens compression. The SIH is attractive for practical applications since most of the energy propagates in the air gap between the two surfaces and, therefore, it features low dielectric losses. Thanks to glide symmetry, the proposed metasurface demonstrates a further enhanced effective refractive index with lower dispersion over an ultra-wide bandwidth in comparison to its non-glide counterpart. A multimodal transfer-matrix approach is here employed to carry out the Bloch analysis of the proposed SIH.

中文翻译：

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压缩超宽带Luneburg透镜的各向异性滑行对称基片结合有孔的亚表面

提出了一种基于滑翔对称性的各向异性晶胞，用于定制设计光学转换的Luneburg透镜的超颖表面。由于进行了光学变换，镜头尺寸减小了25％。拟议中的镜头是超宽带的，它涵盖了多个倍频程频段。所需的本构材料是在由顶部和底部滑行对称超颖表面界定的气隙中实现的；即，它们偏移了一半的时间。每个表面均采用标准印刷电路板技术实现，其单位单元由接地的基板组成，该基板具有椭圆形的多孔顶部包层，并被金属化通孔包围。这项技术被称为基板集成孔（SIH），模拟在平行板上钻的孔的操作，但提供了透镜压缩所需的更高的有效折射率。SIH对于实际应用很有吸引力，因为大多数能量在两个表面之间的气隙中传播，因此具有低介电损耗的特征。由于具有滑行对称性，与非滑行对应物相比，拟议的超颖表面显示出在超宽带宽上具有更低色散的进一步增强的有效折射率。这里采用多峰传递矩阵方法对所提出的SIH进行Bloch分析。与非滑模对应物相比，拟议的超颖表面表现出了更高的有效折射率，并且在超宽带宽上具有更低的色散。这里采用多峰传递矩阵方法对所提出的SIH进行Bloch分析。与非滑模对应物相比，拟议的超颖表面展示了在超宽带宽上具有更低色散的进一步增强的有效折射率。这里采用多峰传递矩阵方法对所提出的SIH进行Bloch分析。