Electromagnetic excitation of a wire enclosed in a rectangular cavity by a plane wave incident on a small aperture

Analysis of the electromagnetic excitation of a conducting wire, enclosed in a rectangular cavity, by an incident plane wave through a small aperture is presented. Two approaches, the method of moments and the equivalent circuit theory, are used to calculate resonant frequencies and the wire current. Bethe’s small–hole theory and thin wire approximation are employed to simplify the numerical computations. When the plane wave excites a resonant mode of the cavity, substantial numerical simplifications are afforded. Under resonance condition, the wire current is much larger than it would be if the wire was in free space. Comparisons of various physical quantities evaluated by these two approaches are made.