Influence of the Spot-Size and Cross-Section on the Output Fields and Power Density Along the Straight Hollow Waveguide

This paper presents a rigorous approach for the propagation of electromagnetic (EM) fields along a straight hollow waveguide with a circular cross section. The objectives are to present the technique to calculate the dielectric profiles and their transverse derivatives in the inhomogeneous cross section of the cylindrical hollow waveguide, and to understand the influence of the spot-size and cross section on the output fields and output power density. The derivation is based on Maxwell's equations. The longitudinal components of the fields are developed into the Fourier-Bessel series. The transverse components of the fields are expressed as functions of the longitudinal components in the Laplace plane and are obtained by using the inverse Laplace transform by the residue method. The separation of variables is obtained by using the orthogonal-relations. These objectives contribute to the application of the model for the straight hollow waveguide.