Mode-converting metasurfaces are passive, lossless devices that can be designed to transform a set of incident modes to a desired set of transmitted modes. In this paper, mode-converting metasurfaces are utilized to synthesize arbitrary, azimuthally-invariant TM apertures. The methods presented in this work can be used to design antennas that can meet specific near-field and far-field criteria unlike most metasurfaces which solely manipulate the far field. The proposed antennas consist of a coaxially-excited, radial cavity topped by the mode-converting metasurface. The main role of the mode-converting metasurface is to establish the desired aperture by converting the modal distribution of the excitation to that of desired aperture. Its secondary role is to impedance match the coaxial feed to the radial cavity. Using modal network theory, an optimization-based design procedure is developed to synthesize the proposed metasurface antennas. The admittance profiles of the electric sheets that comprise the metasurface are optimized to establish the desired aperture profile. To illustrate the design procedure, a radial Gaussian beam antenna is synthesized at 10 GHz and its performance is verified using a full wave electromagnetic solver. The proposed antenna has a height and weight advantage over Gaussian beam horn antennas.

中文翻译：

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使用模式转换超表面进行天线孔径合成


模式转换超表面是无源、无损设备，可将一组入射模式转换为一组所需的传输模式。在本文中，利用模式转换超表面来合成任意的、方位角不变的TM孔径。这项工作中提出的方法可用于设计满足特定近场和远场标准的天线，这与大多数仅操纵远场的超表面不同。所提出的天线由同轴激励的径向腔组成，顶部是模式转换超表面。模式转换超表面的主要作用是通过将激励的模态分布转换为所需孔径的模态分布来建立所需孔径。它的次要作用是对径向腔的同轴馈电进行阻抗匹配。使用模态网络理论，开发了基于优化的设计程序来合成所提出的超表面天线。构成超表面的电介质片的导纳分布被优化以建立期望的孔径分布。为了说明设计过程，在 10 GHz 下合成了径向高斯波束天线，并使用全波电磁求解器验证了其性能。所提出的天线比高斯波束喇叭天线具有高度和重量优势。