How to extracte Qe by Eigenmode solver in HFSS or CST ?

It is very convenient to extract Qe by eigenmode solver when designing a dielectric resonator filter, because the resonant frequencies and the field distribution of the resonant modes can be simultaneously got.How should we set the boundary in order to run Eigenmode Solver because the Eigenmode solver doesnot analyze the open structure?How can we get the Qe?Do you give me a example(such as dielectric-loaded cavity excited by a coax) in detail?

Thanks in advance!