Deformation of the horizontal radiation pattern of TV transmitting antennas due to a thin dielectric radome

Two methods are presented to study the effect of a thin dielectric radome on the horizontal radiation pattern of TV transmitting antennas. Examples are given for two antenna systems, each consisting of four columns of horizontal dipoles supported by a perfectly conducting carrier post of either circular or square cross section. The radome is a thin circular cylindrical dielectric shell enclosing the antenna system. The problem is modeled by a two-dimensional system and two different surface formulations are used to determine the effect of the radome on the radiation pattern. The procedure developed is general; the post and the radome may be of arbitrary cross sections. The noncircularity of the radiation pattern is computed for transmitting antennas in TV bands IV and V (f=470-790 MHz). It is observed that the presence of a radome does not always imply degradation in the circularity of its pattern; it may even enhance the pattern circularity at some frequencies