Integral equation solutions for the radiation from a waveguide through a dielectric slab

The radiation from a waveguide through a dielectric slab has been analyzed by using the integral equation formalism. The integral equations are solved by the generalized method of moments to obtain the aperture electric field, from which the reflection coefficients, radiation patterns, and the degree of surface wave excitation are calculated. It is found that the presence of the dielectric slab causes the higher order modes to be strongly excited in the aperture, and that they must be included for proper determination of the various quantities of interest. This is particularly so when thin dielectric slabs of high dielectric constant are used. Numerical results are obtained to illustrate the effects of dielectric slabs on the radiation characteristics of the antenna.