The paper deals with the evaluation of Sommerfeld integrals that appear in the rigorous analysis of radiating objects embedded in a layered medium. The discrete images of a horizontal electric dipole above or within a multilayered medium, can be obtained by numerically approximating the kernel in a Sommerfeld type integral, using a series of exponential functions with different complex coefficients. The distance limitation of the image theory expression is eliminated by cooperating the contribution of the surface waves. The validity of the image theory is examined by the method of numerical integration.