How does a bended circular waveguide transform TE and TM modes?

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Discussion Overview

The discussion revolves around the transformation of TE and TM modes in a bended circular waveguide, specifically focusing on mode coupling theory and the implications of symmetry principles. Participants explore theoretical aspects, potential applications, and challenges related to mode conversion and reflection in waveguides.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants reference an article discussing how a bended circular waveguide can transform a TE01 mode into a TM11 mode, noting the presence of spurious modes during this process.
  • Questions are raised about whether the same bended pipe can transform TE modes into TM modes and vice versa, based on temporal reverse symmetry.
  • Participants discuss the implications of parity/mirror symmetry, suggesting that cutting the converter and closing one end could lead to a TM reflected mode when a TE mode is injected at the open end.
  • Clarifications are made regarding the distinction between HE11 and TM11 modes, with some asserting that mode transitions should operate in both directions due to reciprocity considerations.
  • Concerns are expressed about the difficulty of separating the two modes present at the port in a reflection-type mode converter.

Areas of Agreement / Disagreement

Participants express varying views on the nature of mode transformations and the implications of symmetry principles. While some agree on the reciprocity of mode transitions, others highlight the complexities and challenges involved, indicating that the discussion remains unresolved.

Contextual Notes

Limitations include the potential for spurious modes, the need for further clarification on the separation of modes in reflection-type converters, and the dependence on specific definitions of modes discussed.

Ricvil
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http://ir.hfcas.ac.cn/bitstream/334002/12022/1/Mode%20converters%20for%20generating%20the%20HE%2011%20%28gaussian%20like%29%20mode%20from%20TE%2001%20in%20a%20circular%20waveguide.pdf
In the above article, the mode coupling theory shows how a bended circular waveguide transforms a TE01 mode into a TM11 mode.
Of course, always will be spurious modes in the process.
My questions are about :
1- By temporal reverse symmetry , the same bended pipe can transform both TE into TM and TM into TE modes?
2-By Parity/mirror symmetry, if one cuts the same converter at it's half length and close one of the ends with the same metal of the waveguide, then if one inject a TE mode at the other open end, one gets a TM reflected mode?
 
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Ricvil said:
http://ir.hfcas.ac.cn/bitstream/334002/12022/1/Mode%20converters%20for%20generating%20the%20HE%2011%20%28gaussian%20like%29%20mode%20from%20TE%2001%20in%20a%20circular%20waveguide.pdf
In the above article, the mode coupling theory shows how a bended circular waveguide transforms a TE01 mode into a TM11 mode.
Of course, always will be spurious modes in the process.
My questions are about :
1- By temporal reverse symmetry , the same bended pipe can transform both TE into TM and TM into TE modes?
2-By Parity/mirror symmetry, if one cuts the same converter at it's half length and close one of the ends with the same metal of the waveguide, then if one inject a TE mode at the other open end, one gets a TM reflected mode?
HE11 is not the same as TM11. However, I am sure the mode transition must operate in both directions by reciprocity considerations, and also in the reflection method you describe.
 
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tech99 said:
HE11 is not the same as TM11. However, I am sure the mode transition must operate in both directions by reciprocity considerations, and also in the reflection method you describe.
Thank you for the answer.
About the HE11 in the article, it is obtained from TM11 resulting from the first stage of conversion, TE01-TM11-HE11.
 
Ricvil said:
Thank you for the answer.
About the HE11 in the article, it is obtained from TM11 resulting from the first stage of conversion, TE01-TM11-HE11.
Thanks for the clarification.
In the case of the reflection-type mode converter. I cannot see how you can easily separate the two modes present at the port.