Phase correction by dielectric slabs in sectoral horn antennas

Beginning with Maxwell\´s equations, the field components and propagation constants are found inside a plane aperture -plane sectoral horn antenna containing two dielectrics. The horn is assumed to be fed from a waveguide containing the dominant mode. Knowing the phase constants in the two dielectrics makes it possible to calculate the dimensions of a triangular-shaped dielectric slab which, when placed in the horn, can alter the curved phase front and produce an approximation to a uniform-plane phase front at the aperture of the horn. This improved phase front results in an improved far field pattern.