Electromagnetic Field Coupling to a Thin Wire Located Symmetrically Inside a Rectangular Enclosure

This paper calculates the current in a conductor inside a cavity, which is induced by lumped and distributed sources. The current is obtained both analytically (Green´s function method) and numerically (multilevel fast multipole method). A long parallel wire is chosen that connects two opposite walls of a rectangular resonator. Since the conductor preserves the translational symmetry of the resonator in one principal direction, the current and the total exciting electrical field can be derived from spatial Fourier series formulations. The obtained results clearly show the influence of the walls on the induced current. Resonance peaks of the resonator, which do not arise in normal electromagnetic compatibility laboratory tests, occurred in the current spectra. The numerical results agree very well with the analytical ones; however, the results are obtained much faster using the analytical formulae (by a factor of 1000).