You can use that expression for Beta = acos((1-S11*S21+S12*S21)/(2*S21))

it's a formula for plotting the dispersion diagram.

I think you should get the S11 and S12 with the simulator then import it into the MATLAB then get the appropriate result.

;-))))

Iran- Semnan university

https://electricalengtutorial.blogspot.com/2016/05/dispersion-diagram-propagation-constant.html

You follow my attachment, wish you success. 

Jaghargh Sir, Where to write Beta expression in CST i.e. Sir in post-processing how I could define this expression.

With Regards,

VK Vishwakarma