Hi all, Can anyone provide a reference (textbook or paper) giving the full field solution (or the on-axis solution at least) of a plane wave incident on an infinite, perfectly-conducting screen with a circular aperture with a radius comparable to the wavelength of the incident wave? I have looked up several papers written by Bethe, Bouwkamp and Brillouin, however they only discuss the formalisms and not the solutions themselves. Bouwkamp hinted that he derived an exact solution in one of his earlier papers, however the paper is quite old (1953) and I don't seem to be able to get access too it. Also, can anyone confirm whether Bouwkamp's solution is correct? Thanks in advance, Claude.