Problem with directional coupler design equations

[beta3]

Hi anyone
I'm designing a coupled line directional coupler. In the design procedure, I have two nonlinear equations to be solved. I tried to solve this equations with 'solve' function in matlab, but the given answers are not true. I also used the 'ezplot' function to solve the equations, but it shows numerous intersections between two plot of equations. the answers given by 'sovle' function are approximately -220 and 96, but the true answers are approximately 0.02 and 0.06 ! the equations are attached. plz help!
View attachment New Text Document (2).txt

 

[FvM]

A nonlinear solver doesn't necessarily find the solution without additional help, e.g. range constraints. I'm sure that the matlab help can tell you a lot about the problem.

It's a nice try to enter a complex equation and start "solve", but it only works in simple case.