This paper discusses the application of metasurfaces for three different classes of antennas: reconfiguration of surface-wave antenna arrays, realization of high-gain polarization-reconfigurable leaky-wave antennas (LWAs), and performance enhancement of van Atta retrodirective reflectors. The proposed surface-wave antenna is designed by embedding four square ring elements within a metasurface, which improves matching and enhances the gain when compared to conventional square-ring arrays. The design for linear polarization comprises of a 1 × 4 arrangement of ring elements, with a 0.56$\lambda$ spacing, placed amidst periodic patches. A 2 × 2 arrangement of ring elements is utilized for reconfiguration from linear to circular polarization, where a similar peak gain with better port isolation is realized. A prototype of the 2 × 2 array is fabricated and measured; a good agreement is observed between simulations and measurements. In addition, the concepts of the design of polarization-diverse holographic metasurface LWAs that form a pencil beam in the desired direction with a reconfigurable polarization are discussed. Moreover, recent developments incorporating polarization-reconfigurability in metasurface LWAs are briefly reviewed. In the end, the theory of van Atta arrays is outlined and their monostatic RCS is reviewed. A conventional retrodirective array is designed using aperture-coupled patch antennas with a microstrip-line feeding network, where the scattering from the structure itself degrades the performance of the reflector. This is followed by the integration of judiciously synthesized metasurfaces to reconfigure and improve the performance of retrodirective reflectarrays by removing the above-mentioned undesired scattering from the structure.

中文翻译：

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用于重新配置多极化天线和Van Atta反射器阵列的超颖表面

本文讨论了超表面在三种不同类别的天线中的应用：表面波天线阵列的重新配置，高增益极化可重新配置的漏波天线（LWA）的实现以及van Atta定向反射器的性能增强。提出的表面波天线是通过将四个方形环元件嵌入超颖表面而设计的，与传统的方形环阵列相比，它可以提高匹配度并增强增益。线性极化的设计包括1×4的环形元件排列，以及0.56$\lambda$间隔，放置在周期性补丁中。环形元件的2×2排列用于从线性极化到圆极化的重新配置，其中实现了相似的峰值增益和更好的端口隔离。制作并测量2×2阵列的原型；在仿真和测量之间观察到良好的一致性。此外，还讨论了偏振多样的全息超表面LWA的设计概念，这些偏振LWA在期望的方向上以可重构的偏振方向形成笔形光束。此外，简要回顾了将极化可重构性整合到超表面LWA中的最新进展。最后，概述了范阿塔阵列的理论，并对其单静态RCS进行了综述。使用具有微带线馈电网络的孔径耦合贴片天线设计常规的逆向阵列，其中结构本身的散射会降低反射器的性能。随后是通过明智地合成的超颖表面的集成，以通过从结构中消除上述不希望的散射来重新配置和改进后向反射阵列的性能。