Application of the method of Kobayashi potentials (KP) is extended to the electromagnetic (EM) diffraction from the parallel-plate T-junction. Standard integral identities are used for problem formulation, without direct usage of Weber-Schafheitlin (WS) integrals. The Fourier function space is exploited for the construction of the governing linear equations. A simple strategy is suggested for the evaluation of the required improper integrals. Numerical results are validated through convergence analysis.