Design Combline filter

I want to design Design Combline. I practised followed the A Practical Design of Lumped, Semi-Lumped and Microwave Cavity Filters (Dhanasekharan_Natarajan'book) with Hfss Software but i don't know how to turning length of skew to achieve results?
Please help me.

I found the document : http://www.swfilterdesign.com/Narrow...ter_Design.pdf . And i simulate follow this document. But when i simulated Coupling Coefficients (2 resonator, See the document), I don't achieve result in 3,44 GHz.
Please help me .

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