need for help with microtrip coupling coefficient

Recently I was designing a microstrip line interdigital filter with tapped line, but I don't know how to calculate the coupling coefficient between coupled lines, can someone help me

when two microstrip lines are coupled, they exhibit even and odd mode(please refer any basic microwave engineering book), each of these modes result in separate impedances ,Zoe and Zoo such that Zo=√(Zoe.Zoo)=50 ohms(approx.)


Now you need to know these values to find coupling coeff.
C=(Zoe-Zoo)/(Zoe+Zoo)

Zoe and Zoo depend upon Width ,gap, length of coupled microstrip lines ,thickness and εr of board plus frequency of operation. Use LineCal in ADS to find all these values.

Thank you very much,i know it now