circular waveguide mode suppression

Question

circular waveguide mode suppression

mwave (Electrical)

(OP)

15 Apr 04 13:35

Hi

I have a circular waveguide which can propagate both TE11 and TM01 modes due to its diameter. I would like to be able to suppress the TM01. Are there any easy classical ways of doing this? I cannot make the waveguide any smaller by the way...

thanks

GOTWW (Industrial) · Answer 1 · 2004-04-16 02:38:38

You really can not beat the old MIT rad lab series when it comes to moding filters, best check there.

Brute force mode filters short out the E-field, orthoganal to the desired mode E-field. others can use lossy materal parallel.

My initial guess, I have none of the reference materials at hand, But TM01 has a circular E-field, bessel functioned.

Insert a printed circuit, low ER, with thin printed copper circles, that correspond to the peak of J01 function.

If neccessary, l/4 matching can be incorporated to lower the TE insertion loss.

mwave (Electrical) · Answer 2 · 2004-04-16 06:08:20

Thanks GOTWW for the insight

However, the mode I have (which I'm pretty sure is TM01) has a radial e-field pattern, not circular.

I'll try & track down the MIT radiation labs titles again...

thanks

GOTWW (Industrial) · Answer 3 · 2004-04-16 14:36:38

You are right, sorry. This complicates matters quite a bit.

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circular waveguide mode suppression