Determination of the resonant frequencies in a complex cavity using the scattering matrix formulation

• Published in: IEEE transactions on microwave theory and techniques Vol. 37; no. 8; pp. 1165 - 1170
• Main Authors: Neilson, J.M., Latham, P.E., Caplan, M., Lawson, W.G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.08.1989; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Boundary conditions; Circuit properties; Eigenvalues and eigenfunctions; Electric, optical and optoelectronic circuits; Electronics; Equations; Exact sciences and technology; Laboratories; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Region 2; Resonance; Resonant frequency; Scattering; Transmission line matrix methods; Waveguide transitions; Diffusion matrix; Resonance frequency; Cavity resonator; Waveguide junction; Numerical calculation; Waveguide; Calculating method
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/22.31074

A method for computing the resonant frequency in a complex cavity consisting of a series of waveguide sections is derived. The analysis is restricted to transitions in which one waveguide is wholly contained in the other. An eigenvalue problem is formed by cascading the scattering matrix from a given section outwards to the ends of the complex cavity, with appropriate boundary conditions at the ends. The eigenvalue equation is solved numerically by searching for a complex frequency, the cavity Q being determined by half of the ratio of the real to the imaginary part of the frequency. The technique is easily implemented numerically and shows good agreement with experiment. This method is suitable for modeling both abrupt changes in radius and smoothly varying tapers.< >