On characteris modes of a circular hole in a cunducting plane

The problem of coupling from one region to another through an aperture in a conducting wall is an important one in the theory of electromagnetic compatibility and interference. This problem was formulated in terms of two admittance operators, one for each region, applying the equivalence principle. These operators are complex and symmetric. In the characteristic modeo theory suggested by Harrington [1], the real eigenvalues of the generalized problem we the imaginary part of the modal admittances and the real weighted orthogonal eigenvectors are the equivalent magnetic currents in the aperture. This theory was applied for some special problems, such like slot in a conducting plane [2] and slot in a conducting cylinder [3], both for the TE end TM cases of excitation. The mutual coupling between two circular holes in a conducting screen is considered in [4].