Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

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• 作者：S. C. Schaub ; M. A. Shapiro ; R. J. Temkin
• 关键词：Corrugated waveguide ; Taper ; mm wave ; THz ; Gyrotron
• 刊名：International Journal of Infrared and Millimeter Waves
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：37
• 期：1
• 页码：100-110
• 全文大小：533 KB
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• 作者单位：S. C. Schaub (1)
  M. A. Shapiro (1)
  R. J. Temkin (1)
  
  1. Plasma Science & Fusion Center, Massachusetts Institute of Technology, 167 Albany St., Bldg. NW16, Cambridge, MA, 02139, USA
  
• 刊物类别：Physics and Astronomy
• 刊物主题：None Assigned
• 出版者：Springer New York
• ISSN：1866-6906

文摘

Simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a ₂ to a ₁, with a ₁<a ₂, the optimal length of the taper is 3.198a ₁ a ₂/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE ₁₁ mode in an optimized taper is \(0.0293 (a_{2}-a_{1})^{4}/{a_{1}^{2}}{a_{2}^{2}}\). These formulae are accurate when a ₂≲2a ₁. Slightly more complex formulae, accurate for a ₂≤4a ₁, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a ₂≤2.12a ₁ and less than 0.1 % when a ₂≤1.53a ₁. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Parabolic tapers may provide lower loss, but linear tapers with moderate values of a ₂/a ₁ may be attractive because of their simplicity of fabrication. Keywords Corrugated waveguide Taper mm wave THz Gyrotron