A Broadband Circular TE } Mode Converter Using Highly Deformed Circular Waveguide

• Published in: IEEE transactions on electron devices 2024-10, p.1-7
• Main Authors: Liu, Zhenwei, Wu, Zewei, Zhang, Ran, Liu, Guo, Wang, Jianxun, Wang, Tieyang, Song, Fangfang, Fang, Shuanzhu, Luo, Yong
• Format: Article
• Language: English
• Subjects: Bandwidth; Broadband; Broadband communication; circular TE<inline-formula xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <tex-math notation="LaTeX"> _{\text{01}}</tex-math> </inline-formula> mode; Circular waveguides; Couplings; Deformation; Electric fields; gyro-TWTs; highly deformed circular waveguide (CW); mode converter; mode purity; Perturbation methods; Power dividers; Propagation losses; Testing
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2024.3478195

A method for broadening the operating bandwidth of circular TE _{\text{01}} mode converter is proposed by using highly deformed circular waveguide (CW). The influence of deformation on the field patterns and the mode spectrum is investigated, and the maximum mode spectral gap between the TE _{\text{01}} mode and the undesired modes is deduced. According to the analysis, a K -band circular TE _{\text{01}} mode converter using highly deformed CW is designed, fabricated, and measured. The results show that conversion efficiency of a single mode converter higher than 89.1%, the reflection better than - 20 dB, and the mode purity exceeds 98.7% within a relative bandwidth of 40.35%. The angle-independent transmissions demonstrating high mode purity and the appearance of TE _{\text{01}} mode is confirmed by the near-field pattern measurement. The mode converter features broad bandwidth, high mode purity, and compactness, which can be applied to cold-test experiments of gyro-TWT components and the high-power transmission line devices.