#### zhul3

##### Member level 5

**hfss how obtain q resonator**

Hi guys,

I am using HFSS to design a 4-pole coaxial cavity filter.

Now I am in the last step designing the feedline of the filter. (please see the pic.) I set a PML boundary on the coaxial line and sweep its "height" to achieve a desirable Loaded Q.

Equations

QL=sqrt(im_f^2+re_f^2)/(2*im_f),

im_f=(im(Mode(1))+im(Mode(2)))/2

re_f=(re(Mode(1))+re(Mode(2)))/2

are used in the solver for calculating loaded Q. (The parametric sweeping (10 passes) takes super long time with the PML boundary.....)

Surprisingly, I noticed that after setting a PML boundary, a "eigen Q" option is appearing in the solver setup window and gave Q values of each mode after simulation.

My question is, what do these "Eigen Qs" mean? Unloaded Q or Loaded Q?

Can I just set one mode and simulate its Eigen Q, then consider such Q as loaded Q instead of calculating it with the above equations?

Thanks very much.

Thanks