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Problem with S11 parameter

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I created in Comsol a resonator cavity with a feed (in the picture) that works at GPS frequency (1.57 GHz). When I try to extract S parameters I don't understand the behavior because the values are very high (as you can see in picture). Can somebody help me?


2 Replies Last Post 9 oct. 2016, 15:36 UTC−4

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Posted: 8 years ago 9 oct. 2016, 14:25 UTC−4
I agree that number looks weird. What do the fields look like inside the cavity? What are your materials? Is there lossy material anywhere? How did you decide what frequency to the cavity resonates at, did you do a sweep?
I agree that number looks weird. What do the fields look like inside the cavity? What are your materials? Is there lossy material anywhere? How did you decide what frequency to the cavity resonates at, did you do a sweep?

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Posted: 8 years ago 9 oct. 2016, 15:36 UTC−4

I agree that number looks weird. What do the fields look like inside the cavity? What are your materials? Is there lossy material anywhere? How did you decide what frequency to the cavity resonates at, did you do a sweep?


Cavity size has been designed by considering fondamental TE mode. I've used a coaxial cable as feed with a little extension of inner conductor to couple energy inside the cavity. I've simulated a frequency range between 1.45[GHz] and 1.65[GHz]. However, you can see the field in the picture below.
Cavity has air inside and PEC as boundary.
[QUOTE] I agree that number looks weird. What do the fields look like inside the cavity? What are your materials? Is there lossy material anywhere? How did you decide what frequency to the cavity resonates at, did you do a sweep? [/QUOTE] Cavity size has been designed by considering fondamental TE mode. I've used a coaxial cable as feed with a little extension of inner conductor to couple energy inside the cavity. I've simulated a frequency range between 1.45[GHz] and 1.65[GHz]. However, you can see the field in the picture below. Cavity has air inside and PEC as boundary.

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