We derive the field equivalence principle for electromagnetic waves propagating in a heterogeneous generally bianisotropic medium. For the given medium, we define the complementary medium corresponding to the transposed constitutive matrix. We define the frequency-domain complementary Green function as the frequency-domain Green function in the complementary medium but with the opposite sign at the time derivative. We then derive the provisional field equivalence principle as the relation between the frequency-domain wave field in the given medium and the frequency-domain complementary Green function. This provisional field equivalence principle yields the reciprocity relation between the frequency-domain Green function and the frequency-domain complementary Green function. The final version of the field equivalence principle is then obtained by inserting the reciprocity relation into the provisional field equivalence principle.
Electromagnetic waves, heterogeneous media, bianisotropic media, constitutive tensor, magnetic vector potential, electric potential, Green function, field equivalence principle, reciprocity relation.
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