Grazing wave diffraction by a PEC or PMC rectangular cylinder

In a previous publication (B. Morse. Diffraction by polygonal cylinders. Jour Math Physics 5(2)(1964)p199) Morse used existing asymptotic results derived by Oberhettinger for wedge diffraction, to solve by the Keller method, diffraction by polygonal cylinders. In particular the PEC and PMC rectangular cylinder. For grazing incidence when the EM wave is incident along one of the side faces the normal Keller method breaks down. An alternative method was used to overcome this situation. The method used was not rigorous, in that integrals representing the diffracted field were evaluated even though they were divergent. In order to deal with an impedance cylinder the present author found the method proved unworkable and so another technique had to be used. To compare the results of the impedance cylinder in the limit of becoming a PEC or PMC I needed to be confident that the results of Morse were correct. This talk gives an alternative approach that does not involve dealing with divergent integrals to verify the results obtained by Morse.