Comparative analysis of approximate and exact solutions of transient wave radiation problems

Abstract

The problem of transient wave radiation from open end of a coaxial waveguide is solved by means of the modal basis method in time domain. The analytical expressions of fields radiated into free space and reflected inside the waveguide are obtained for step-wise time dependence of amplitude of the exciting TEM-wave. The solution for exciting TEM-wave with arbitrary time dependence of amplitude is obtained by calculation of Duhamel's integral. The exact solution of the problem is compared with the same one obtained in Kirchhoff approximation. The spatial and time dependencies of the field radiated from the coaxial aperture are obtained experimentally to examine theoretical results. A comparative analysis of the theoretical and experimental results is made.