Influence of circular-polarized waveguide radiator length on amplitude and polarization beam patterns

The change of amplitude and polarization patterns of the circularly polarized radiator in form of the open end of a circular waveguide in dependence on its length was studied experimentally with help of a rotating indication linearly polarized antenna. It is shown that if the radiator length is more than quarter-wavelength in free space, the characteristics of the waveguide radiator are approximately the same as for the half-infinite waveguide.