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

In this paper, 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 a2 to a1, with a11a 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$$2\atop{1}$$1a$$2\atop{2}$$. These formulae are accurate when a2≲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. Finally, 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.
Authors:
ORCiD logo [1] ;  [1] ;  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science & Fusion Center
Publication Date:
Grant/Contract Number:
FC02-93ER54186
Type:
Accepted Manuscript
Journal Name:
Journal of Infrared, Millimeter, and Terahertz Waves
Additional Journal Information:
Journal Volume: 37; Journal Issue: 1; Journal ID: ISSN 1866-6892
Publisher:
Springer
Research Org:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Corrugated waveguide; Taper; mm wave; THz; Gyrotron
OSTI Identifier:
1343560