The dielectric loaded horn radiators are commonly used in various applications due to their distinguished features, such as low cross-polarization, pattern symmetry and simple production. The analysis of this kind of horn, mode matching (MM) and integral equation methods have been preferred in the literature. In the present study, the radiation of plane harmonic scalar waves from a dielectric loaded circular horn radiator is treated by using the mode matching method in conjunction with theWiener-Hopf technique. The solution is exact but formal since infinite series of unknowns and some branch-cut integrals with unknown integrands are involved. Approximation procedures based on rigorous asymptotic are used and the approximate solution to the Wiener-Hopf equations are derived in terms of infinite series of unknowns, which are determined from infinite systems of linear algebraic equations. Numerical solution of these systems is obtained for various values of the parameters, of the problem. Their effect is presented on the directivity of the circular feed horn. © 2007 ACES.