CPW Butterfly Radial Stub

Hi dear friends,
I need equations for designing a CPW butterfly radial stub. I found just on paper in the net, but it doesn't provide formulas for calculating the input admittance. Moreover I checked in 'Coplanar Waveguide Circuits, Components, and Systems' but this book doesn't provide formulas for calculating the input admittance. I need it for a broadband matching network of a max gain amplifier, thus i need to design the radial stub starting from the desired input admittance value.

Any tip for drawing it in Ansoft Designer?

Thanks a lot.

I.