cpw equivalent circuit

Hi tehre.
please help me:
I designed an antenna with cpw on back of substrate and a patch on substrate.
I want to find its equivalent circuit.
I used the book "Coplanar Waveguide Circuits,Components,and Systems" to find formulas but I couldnt deceide which one to use?!
ground backed cpw formulas or simple cpw formulas?!

can you give a schrma or pic of ur design

the substrate has h=1 and the material is FR4.

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just keep the square patch on substrate on transfer the cpw feed (strip and two grounds) to the back of substrate