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Waveguide filter based on resonator: External quality factor
Posted Aug 25, 2015, 11:23 a.m. EDT RF & Microwave Engineering Version 4.4, Version 5.0, Version 5.1 0 Replies
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I try to design a waveguide filter based on resonant cavities. From the filter theory I can obtain the needed coupling factors between the cavities and the needed external quality factor between the first/last cavity and the waveguide. My question is now, how can I numerically obtain the external quality factor between the waveguide and the first resonator. I know that it is related to the phase of the S-Parameter at the waveguide port. But somehow I struggle to set up the simulation. I ran simulation with a geometry as indicated in the attached sketch. (The waveguide port is at the "longer end". "The shorter" one is the resonant cavity and the are connect by a very short thin bar. I would like to use the crossection of the bar to control the coupling between waveguide and cavity.) But I found strange peaks in the phase of S11 (see attached plot) which I cannot interpret. I would be very grateful for any hint on how to calculate the external quality factor.
Thanks a lot in advance
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Hello Felix
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