General integral identities for bianisotropic media and related equations, properties, and coupling expressions

We consider advanced properties of electromagnetic fields derived from integral identities in bianisotropic media : generalized reciprocity principle for adjoint systems, equivalence of surface sources, uniqueness, links between impedance surface for adjoint systems, fields influenced by a perturbation of a system, and fields due to the coupling between two arbitrary scatterers perturbating a complex bianisotropic system, which generalizes our previous method [1]. As an example of application of our results on couplings for bianisotropic systems, we consider the case of the evaluation of the radiation of a cavity inserted in an infinite plate, when, in practice, the ends of the plate perturb the result, and then present an efficient method which permits the numerical suppression of the first order couplings by a simple and efficient postprocess. Thus, we can recover the scattering diagram of a cavity when it is inserted in a plane (i.e. in the plate without ends), in a simple manner at any observation angle. Our method remains efficient for backscattering, from grazing to normal angles, in contrast of well-known difficulties at grazing incidence of common time domain filtering methods.