Characteristic mode analysis of aperture antennas based on duality principle

Characteristic mode analysis (CMA) of metallic antennas has been studied for many years. CMA of aperture antennas is usually based on the equivalent magnetic current method but the solver is not available from main-stream solvers. In this paper, the problem is studied for the first time through the duality principle. Eigenvalues, magnetic current distribution of arbitrary aperture antennas can be obtained by the CMA of its complementary form. Formulation of the method is given and the relationship between aperture and its complementary form is verified by numerical examples.