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

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A bended circular waveguide can transform TE01 modes into TM11 modes, as demonstrated by mode coupling theory. The discussion raises questions about the reversibility of this transformation, suggesting that the same waveguide could convert TM modes back to TE modes due to temporal reverse symmetry. Additionally, it explores the concept of parity/mirror symmetry, proposing that cutting the converter and closing one end could allow for the reflection of TM modes when TE modes are injected. The HE11 mode is clarified as a result of the conversion process from TM11, highlighting the complexity of mode transitions. Overall, the conversation emphasizes the intricacies of mode conversion and the challenges in distinguishing between modes in reflection-type converters.
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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.
 

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