Coupling of tilting gaussian beam with hybrid mode in the corrugated waveguide

K. Ohkubo, S. Kubo, H. Idei, M. Sato, T. Shimozuma, Y. Takita

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Abstract

The mode-conversion loss in the matching between the gaussian beam emanated from the gyrotron and the hybrid mode in the circular corrugated waveguide with the diameter of 2a is discussed. By numerical calculation, it is found that the loss considerably increases and optimum waist size w0 changes when TEM00 mode with the wavelength λ is injected with offset or tilt. By fitting numerical data to the polynomial function, it becomes evident that the scaling formulas of the losses for the off-axis shift rd and for the tilt angle θ are derived to be 2.3(rd/a)2 - 2.2(rd/a)4 and 3.9(aθ/λ)2 - 5.6(aθ/λ)4 for fixed w0/a=0.643, respectively. To keep the mode-conversion loss ≤1% for the frequency of 168 GHz and 2a=88.9 mm, tilting angle and offset should be less than 0.1 degrees and 2.9 mm, respectively.

Original languageEnglish
Pages (from-to)23-41
Number of pages19
JournalInternational Journal of Infrared and Millimeter Waves
Volume18
Issue number1
Publication statusPublished - Jan 1997
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Condensed Matter Physics
  • Physics and Astronomy (miscellaneous)
  • Electrical and Electronic Engineering

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