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S21, RF attenuation between two cross-sections

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Hello,

I am trying to simulate a circular wave guide below cut-off to be used as an attenuator. I started with just a cylinder whose boundaries were PECs and each end defined as a port. The S21 followed exponential decay as expected

Now I am exciting the TE11 mode with two parallel wires using a lumped port voltage between them. After simulation I can view the field profile and it is the desired mode. However I would like to know S21 between a short distance after the end of the wires to the end port.

Apparently comsol does not let you define internal boundaries so I am not sure how to do it. I have included a screen shot of my geometry.

Thank you.


1 Reply Last Post Feb 23, 2016, 9:55 a.m. EST

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Posted: 8 years ago Feb 23, 2016, 9:55 a.m. EST
I have tried making a cross-sectional work plane and circle with the same radius as the cylinder, and defining that as a port, and enabling the slit condition. Also i tried defining that as a lumped port with h=0. And I tried calling the the pack plate a port but that failed because of the wires going through it. So no luck with any approach and I cant think what else to do. If anyone has any suggestions for defining ports at arbitrary locations or work arounds to find S21 please reply.
I have tried making a cross-sectional work plane and circle with the same radius as the cylinder, and defining that as a port, and enabling the slit condition. Also i tried defining that as a lumped port with h=0. And I tried calling the the pack plate a port but that failed because of the wires going through it. So no luck with any approach and I cant think what else to do. If anyone has any suggestions for defining ports at arbitrary locations or work arounds to find S21 please reply.

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