Excitation of a circular loop through a small aperture

The problem of determining the current excited on a circular loop which is placed opposite a small circular aperture in a conducting screen, on which an electromagnetic plane wave is incident, is considered. It is shown that this geometry is unusual in that the resulting integrodifferential equation can be reduced to an explicit expression for the current. The total rate of electromagnetic energy flow in the radiation zone is also calculated, as is the angular dependence of the energy flux. Sample results are presented which demonstrate the resonant behavior of the system when the wavelength of the incident wave is equal to the loop circumference.