In particular, if ( J 1 , E 1 ) satisfy Maxwell's equations at ω for a system with materials ( ε ε 1 , μ μ 1 ) , and ( J 2 , E 2 ) satisfy Maxwell's equations at ω for a system with materials ( ε ε 1 T , μ μ 1 T ) , where T denotes the transpose, then the equation of Lorentz reciprocity holds. This can be further generalized to bi-anisotropic materials by transposing the full 6×6 susceptibility tensor.