When an antenna is installed within a dielectric radome, it is desired that the influence of the radome to the radiation pattern and other parameters be as small as possible. However, due to the complicated shape and the presence of the finite dielectric thickness, the installed radiation pattern will eventually be different in some degree from that of the antenna alone in free-space. Hence, accurately predicting the installed radiation pattern is important to characterize the realistic performance of the antenna. Many numerical approaches exist for this purpose. For electrically small sized radomes, the analysis can be easily carried out using many full-wave methods such as presented in [1] and [2] in which the volume integral equation and surface integral equations are used. For electrically large and smooth dielectric radomes, an approximate method called thin dielectric sheet approximation (TDS) introduced in [4] will be very effective to perform the analysis since only a surface integral equation is involved. When a radome is electrically large and smooth (does not have sharp tips and edges), the high frequency method (PO and GTD) can be applied to predict reasonably accurate results. However, in real world problems, a radome is often constructed to have electrically small features and geometry discontinuities which cause reduced prediction accuracy by high frequency methods. In this case, the hybrid approach [5,6] is often used by which the electrically small features (small parts) are analyzed by a full-wave solver and the electrically large and smooth portion (large part) is treated using a high frequency method. The solution accuracy depends on the order of interactions between the small and large parts.
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