Cylindrical ground-clutter shield

A theoretical investigation of the influence of metal shields on antenna radiation patterns is performed. This study allows us to determine the proper dimensions of a circular cylindrical finite perfectly conducting shield placed on the ground around infinitesimal sources located at its axis, in order to reduce the ground-side lobe. Two different methods are applied in this study: 1) integral equation method (IE) and 2) geometrical theory of diffraction (GTD). When the dimensions of the cylindrical shield become very large compared to the wavelength, the first method involves a very large matrix that is impractical for the present computers to handle. Under these circumstances, GTD may be shown to be a very useful approach. For the range of dimensions where both methods are applicable, a comparison between them is made.