Dispersion diagram for Anisotropic EBG in CST MWS

Hello,

I'm trying to generate a dispersion diagram in any direction (for an example, if angle is 60 degree away from x axis, or I want to calculate the phase shift if a surface wave is along this angle)for anisotropic EBG in CST MWS, but not so sure it's right or not.

1.I simulate the EBG dispersion diagram the way as piboo said in this post https://www.edaboard.com/thread123197.html and got a dispersion diagram as he attached there.

while for more details on Gamma to X, X to M, and M to Gamma, mpero in this post https://www.edaboard.com/thread28145.html summarized the way on simulation.

2. But after one get dispersion diagram on Gamma, X, and M, since from Gamma to X corresponding angle=0, and M to Gamma corresponding angle=45 degree, how to understand relationship between dispersion diagram of X to M and angle? and if I need a dispersion diagram of angle=60, could I just set phy=tan(pi/3)*phx and just sweep phy from 0 to 180degree? (here phx=phase shift of x direction, phy=phase shift of y direction)

Thanks for any advice!

Stringtheory