Radiation in Waveguide

Abstract

Chapter 2 investigates the radiation problems in waveguide. The eigenvalue problems in waveguide are approached in transverse field. Various dyadic Green's functions for waveguide are derived directly from the field expansions in terms of the vector modal functions, which avoids a problem caused by the incompleteness of the eigenfunctions selected to expand a dyadic point source in the conventional study of dyadic Green's functions in waveguides. By the equivalence principle, three common waveguide discontinuity problems, the excitation of waveguide, obstacles in waveguide, and the coupling between waveguides, are analyzed and treated as a radiation problem and compactly reformulated by using the dyadic Green's functions. The radiated field in time domain are approached by the vector modal functions, and the transient processes in the waveguide are studied. For reference, the vector modal functions in typical waveguides are summarized.