If Voigt-wave propagation is possible in a dissipative anisotropic dielectric material characterised
by the permittivity dyadic ##IMG##
[http://ej.iop.org/images/0143-0807/37/6/064002/ejpaa3bd4ieqn1.gif] {$\mathop{\varepsilon
}\limits_{\raise{2pt}=}$} , then it is also possible in the analogous energetically active material
characterised by the permittivity dyadic ##IMG##
[http://ej.iop.org/images/0143-0807/37/6/064002/ejpaa3bd4ieqn2.gif] {$\mathop{\tilde{\varepsilon
}}\limits_{\raise{2pt}=}$} , where ##IMG##
[http://ej.iop.org/images/0143-0807/37/6/064002/ejpaa3bd4ieqn3.gif] {$\mathop{\tilde{\varepsilon
}}\limits_{\raise{2pt}=}$} is the hermitian conjugate of ##IMG##
[http://ej.iop.org/images/0143-0807/37/6/064002/ejpaa3bd4ieqn4.gif] {$\mathop{\varepsilon
}\limits_{\raise{2pt}=}$} . This symmetry follows directly from a theoretical analysis of the
necessary and sufficient conditions for Voigt-w…