In this paper, we present an exact analysis of parallel plate-fed slot antennas loaded by a dielectric cylinder. The primary excitation is taken to be either a TE incident mode of the parallel-plate waveguide or an incident E-polarized plane wave. The followed formulation technique leads to singular integral or integrodifferential equations of the first kind which are discretized using quasi-analytical methods. The matrix elements of the resulting system of linear algebraic equations are given either in closed form or via rapidly converging single series. This, in conjunction with the small matrix size required, enables one to obtain very accurate results with low computational cost. Typical numerical results are presented to bring to light the effect of the cylindrical load on the characteristics of the antenna.