Waveguide-fed dielectric spherical antennas

A theoretical method is presented for obtaining the far-field patterns of a feed structure consisting of a homogeneous dielectric sphere placed in front of, but displaced from, the open end of a circular waveguide carrying the TE11 mode. Such a feed, for an optimum value of the sphere offset, has a reduced input v.s.w.r., as indicated experimentally elsewhere. Theoretical expressions are derived for the radiated far-field components of this type of a feed and the results are compared with the experimental data obtained from the test feeds