Transmission-line-matrix solution of waveguides with wall losses

The transmission-line-matrix method of numerical analysis is developed to account for losses in the walls of a waveguide. Results are given in terms of the wave impedance of a waveguide with losses and also in terms of the power decay due to losses in the walls of a resonant rectangular cavity.     

Time domain approximations in the solution of fields by time domain diakoptics

The numerical solution of field substructures in time domain diakoptics requires an interation time consistent with the numerical accuracy required. When storing and reconnecting the substructures, the information required can be obtained from considerably fewer samples. This paper shows how time domain approximations can further reduce the storage and computing time in space approximated time domain diakoptics.     

Numerical solution of lossy waveguides: t.l.m. computer program

The transmission-line-matrix method is a time-domain numerical method for solving wave problems. The method uses a mesh of transmission lines to represent a propagation space, and the losses in the space are accounted for by making the transmission lines lossy. Lossy boundaries are simulated by imperfect boundary reflections on the transmission lines. A FORTRAN program implementing this technique is presented.     

On the stability of symmetric nonlinear output-coupled multivariable systems

A Lyapunov function together with a modified Meyer-Kalman-Yakubovitch lemma are used to develop absolute stability conditions for autonomous symmetric nonlinear output-coupled multivariable systems. The nonlinear characteristics are restricted in both sector and slope. As an example, a coupled-core nuclear reactor with typical parameters is considered to illustrate the concepts developed in this correspondence.     

Transmission-line matrix solution of waveguides with dielectric losses

The transmission-line matrix method is a time-domain numerical method for solving wave problems. This paper describes how a minor change in the computer program for loss-free dielectrics extends the method to include dielectric losses. Results are given in terms of the wave impedance of a waveguide with losses, and also in terms of power decay due to losses in the dielectric of a resonant cavity.     

T.L.M. analysis of the dispersion characteristics of microstrip lines on magnetic substrates using 3-dimensional resonators

The dispersion characteristic for a microstrip line on an isotropic magnetic substrate is calculated by the t.l.m. method. The results indicate how errors obtained using approximate TEM analysis vary with frequency. The results also serve to demonstrate the versatility of the 3-dimensional t.l.m. program.     

Solution of 6-component electromagnetic fields in three space dimensions and time by the t.l.m. method

The extension of the transmission-line matrix method to three space dimensions is described. The technique provides a solution to the complete set of Maxwell's equations and, in particular, describes wave propagation in mixed media, with or without losses. The method is illustrated by obtaining results for the resonance frequency and field decay time of rectangular cavities partially filled with dielectric.     

Dispersion characteristic of a microstrip line with a step discontinuity

The t.l.m. method of numerical analysis in three space dimensions and time has been successfully applied to microstrip problems. In the letter, a general discontinuity problem in the form of an abrupt change of width in a microstrip line is analysed and comparison is made with approximate data in the literature.     

Analysis of a wide range of microwave resonators: t.l.m. methods

The solution of large m.i.c.-subassemblies presents a major problem to any numerical method. However, it would seem that the first step should involve a numerical routine of a very general nature for simple discontinuities in 3-dimensional structures. The letter describes how the t.l.m. method of numerical analysis in the form of a very general computer program fulfils this requirement.     

The use of time domain diakoptics in time discrete models of fields

The principles of diakoptics are extended to time domain solutions and the technique is applied to the solution of fields by introducing space approximating polynomials. Since transmission-line networks provide time-discrete models suitable for exact numerical analysis, the topic is approached by tearing these transmission-line models and then showing how reconnection is made in the time domain.