DUALITY TRANSFORMATIONS AND GREEN DYADICS FOR BI-ANISOTROPIC MEDIA

Duality transformation, defined as a linear transformation between ele ctromagnetic six-vectors, is known to transform electromagnetic proble ms in a linear (bi-anisotropic) medium to electromagnetic problems in another linear medium. This gives a possibility to create analytical e xpressions for the Green dyadic for media which are dual to simpler me dia with known Green dyadic solutions. Different forms of the duality transformation of fields are considered and their properties in terms of eigenfunctions are discussed. After this, corresponding transformat ions to medium parameters are considered in terms of their eigenmedia, i.e., media which are transformed in a simple manner. As a particular example a nonreciprocal anisotropic medium is considered, for which t he Green dyadic was recently constructed in analytic form. It is shown that when the medium is transformed to a nonreciprocal bi-anisotropic medium, its Green dyadic can be obtained through the same transformat ion.