ANALYSIS OF NEARLY CYLINDRICAL ANTENNAS AND SCATTERING PROBLEMS USINGA SPECTRUM OF 2-DIMENSIONAL SOLUTIONS

This paper presents a powerful method to analyze antennas which can be considered principally two-dimensional (2-D) or cylindrical, except f or some three-dimensional (3-D) physical or equivalent sources, e.g., dipoles or slots, It is shown by Fourier transform techniques that suc h antennas can be analyzed as 2-D problems with harmonic longitudinal field variation, The radiation pattern can often be determined directl y from a finite set of such 2-D solutions, each one obtained by any me thod, e.g., the moment method, The mutual interaction between the cyli ndrical scatterer and the sources must be calculated to determine the exact current distribution on the sources and their impedances or admi ttances, This is facilitated by performing an inverse Fourier transfor m of an infinite spectrum of the numerical 2-D solutions followed by a moment method solution in the spatial domain to satisfy the boundary conditions on the 3-D equivalent sources themselves, The inverse Fouri er transform is simplified by the use of asymptote extraction, The met hod is in itself a hybrid technique as one method is used to solve the harmonic 2-D problem, and the other to solve for the source currents.