Wave propagation in anisotropic media

I'm given a wave propagation in an anisotropic medium with the following properties:

$\epsilon=\left[\begin{array}{ccc} \epsilon_{11} & 0 & 0 \\ \epsilon_{21} & \epsilon_{22} & \epsilon_{23} \\ 0 & 0 & \epsilon_{33} \end{array}\right]$

$\mu=\left[\begin{array}{ccc} \mu_{11} & 0 & 0 \\ \mu_{21} & \mu_{22} & \mu_{23} \\ 0 & 0 & \mu_{33} \end{array}\right]$

And we place a perfect conductor in the XY plane. Then I should compute the vanishing components of the electromagnetic field in the XY plane,and if given the current and charge superficial densities, the rest of the componentes of the electromagnetic field.

May I change the coordinates to a diagonal form for both $\epsilon$ and $\mu$ or something?