Scattering of a dipole field by two coaxial segments of a circular waveguide of finite length

The excitation of symmetric oscillations in a system of two coaxial segments of a circular waveguide of finite length by a longitudinal electric dipole is studied analytically and numerically. The analysis is based on the partial operator-inversion method, using the solution of the Riemann-Hilbert problem for two segments of the real axis. The effect of diffraction coupling between the waveguide segments on the spectrum and amplitude of the oscillations is investigated. In addition, attention is given to the effect of a cylindrical screen placed above a plane ideally reflecting surface on antenna radiation in near-horizon directions. The results obtained are compared with those obtained with the geometrical theory of diffraction.