While he is a Professor Emeritus at Ohio State, Professor Kouyoumjian supervised a thesis work by Merih Buyukdura. They first derived a dyadic Green's function for a PEC wedge using spherical wave functions and employed asymptotic approximation. They also derived the extended UTD in which higher order terms in the diffraction matrix are predicted. The thesis was defended in 1984. In this presentation, a brief discussion of edge waves as derived from the asymptotic expansion of dyadic Green's function in terms of spherical functions will be made and afterwards the derivation of extended UTD diffraction coefficients will be given. © 2011 IEEE.