A novel and generalized methodology of mode conversion based on the transmissive metasurfaces is studied in this article. The mathematic formulations, the design criterions, and procedures have been presented in detail. To further demonstrate the proposed methodology, four typical examples are designed. Subsequently, a prototype with the input mode of circular waveguide TM0,1 mode is designed, fabricated, and measured at ${X}$ -band. The simulated and measured results show that the input mode has been converted into the Guassian-like mode, which could verify the correctness of the proposed design methodology. In addition, due to the rich applications of the transmissive metasurfaces, the proposed methodology will start a new page to realize the mode conversion, especially for the high-frequency case.

中文翻译：

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基于透射超表面的模式转换广义设计方法

本文研究了一种基于透射超表面的新型通用模式转换方法。详细介绍了数学公式、设计标准和程序。为了进一步证明所提出的方法，设计了四个典型的例子。随后，设计、制造了输入模式为圆形波导 TM0,1 模式的原型，并在 ${X}$ 波段进行了测量。仿真和实测结果表明，输入模式已转换为类Guassian模式，可以验证所提出的设计方法的正确性。此外，由于透射超表面的丰富应用，所提出的方法将开启新的一页来实现模式转换，特别是对于高频情况。