Transmission Line Matrix Analysis Research Articles

Implementation of a Novel Efficient Hybrid Method for the Analysis of Interference in High Frequency Circuits

A new method for analysis of interference in high frequency has been used for evaluation of the interference of two loop antennas. The method is based on the Transmission Line Matrix (TLM) method augmented with a time-domain integral equation formulation to account for the radiation of equivalent sources and to evaluate the interfering electromagnetic fields. A comparison between this method which is referred as the IRIS method (Interference and Radiation of Internal Surfaces) and different approaches for the Analysis of Interference has been performed. The result of classical TLM analysis and the IRIS method analysis for interfering of loop antennas has been represented.

TLM analysis of a cylindrical metallic cavity excited with a real-feed probe

The influence of feed-probe dimensions on the resonant frequencies in a cylindrical metallic cavity is investigated and presented. Cavity modelling is achieved by using the transmission-line matrix (TLM) time-domain method and a wire node to account for the feed-probe presence. The results of the TLM analysis are validated against the experimental results. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.

TLM analysis of mutual coupling of microstrip patch antenna array

The transmission-line matrix (TLM) method is used to simulate the mutual coupling effect between two rectangular microstrip patch antennas, which are covered with a dielectric layer. A novel graded Heaviside absorbing layer (HAL) is used as the absorbing boundary condition to truncate the computational space. The numerical results obtained are compared with those of the finite-difference time-domain (FDTD) method as well as the published theoretical and experimental results of other authors, and good agreements are obtained.

Toward an optimum design of NRD-guide and microstrip-line transition for hybrid-integration technology

The newly proposed hybrid-integration technology of a nonradiative dielectric (NRD)-guide and planar structure offers an attractive alternative for designing microwave and millimeter-wave integrated circuits and systems. This paper presents an attempt with a transmission-line matrix (TLM) analysis toward accurate design and optimization of the NRD/microstrip-line transitions for the proposed scheme. Electrical performance of the transitions is studied with respect to various parametric effects such as the influence of coupling slot size, NRD and microstrip-line open-ends, as well as dielectric permittivity. Experiments with the designed transitions are made to validate our TLM analysis, as well as to demonstrate good performance. Calculated and measured results suggest that such a hybrid integration have a promising future as high-frequency building blocks.

Autoregressive (AR) and autoregressive moving average (ARMA) spectral estimation techniques for faster TLM analysis of microwave structures

Autoregressive (AR) and autoregressive moving average (ARMA) techniques have been successfully implemented in conjunction with the transmission line matrix (TLM) method for efficient time-domain analysis of microwave structures. The AR technique can be used to compute the full time-domain response from a relatively short segment of the early TLM response. It was found that the least-square technique of estimating the AR parameters requires a shorter time record than solving Yule-Walker equations through the Levinson-Durbin algorithm. The ARMA technique can be used to compute the scattering parameters of microwave structures without using the discrete Fourier transform. A recursive least square covariance ladder algorithm has been used for ARMA modeling. Both AR and ARMA models have been validated by applying them to waveguide and suspended substrate stripline filters. With these techniques, the speed of the computationally intensive TLM algorithm can be increased up to five times. >

A transformed symmetrical condensed node for the effective TLM analysis of guided wave problems

A transmission line matrix (TLM) algorithm for the effective solution of arbitrary guided wave problems is proposed. The algorithm uses an appropriately transformed symmetrical condensed node (SCN) introduced herein. In comparison with the previous SCN TLM formulation for the analysis of guiding structures, the approach maintains equivalent accuracy and generality while providing a 50% gain in terms of required computer memory and time. The advantages of the new algorithm are verified by means of several examples, including full-wave analysis of waveguides filled with anisotropic and lossy media. >

An efficient algorithm for transmission line matrix analysis of electromagnetic problems using the symmetrical condensed node

A study of the symmetrical condensed TLM (transmission line matrix) node is presented. The study reveals not only that the characteristic scattering matrix satisfies the law of conservation of energy but also that electromagnetic fields are conserved even for finite node spacing. Using the results of this study, the authors develop an efficient algorithm for TLM analysis using the symmetrical condensed node. This algorithm significantly reduces the number of floating point operations so that the speed of computation is comparable to that of other expanded node analysis schemes. The case of a lossy medium is also discussed. With a better understanding of this symmetrical node and equipped with a fast algorithm, TLM analysis of three-dimensional electromagnetic problems can improve the computer-aided design of microwave and millimeter-wave circuits. >

Transmission line matrix modeling of disperse wide-band absorbing boundaries with time-domain diakoptics for S-parameter extraction

A numerical modeling procedure based on Johns time-domain diakoptics approach with space interpolation techniques for efficient transmission-line matrix (TLM) analysis of two-dimensional microwave circuits is discussed. Frequency-dispersive boundaries are represented in the time domain by their characteristic impulse response or numerical Green's function (Johns matrix). Almost perfect wide-band absorbing boundary conditions have been obtained with this technique, permitting accurate characterization of waveguide discontinuities and compounds. The application of these techniques saves considerable computer run time and memory when compared with conventional TLM analysis.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Accuracy of TLM Analysis of Finned Rectangular Waveguides

This paper investigates three sources of error affecting the Transmission Line Matrix (TLM) analysis of finned rectangular waveguides. It is shown how truncation and velocity errors can be minimized, and a diagram for maximum coarseness error affecting the TLM analysis is presented. After error correction, cutoff frequencies obtained with the TLM method are in excellent agreement with results obtained with the Transverse Resonance Method.

Transmission-line matrix analysis of continuous waveguiding structures using stepped-impedance cavities

Up to the present time, the t.l.m. method of numerical analysis has found the dispersion characteristics of continuous waveguiding structures by obtaining the resonant frequencies of quarter wavelength cavities. Long cavities requring many nodes have been necessary, and the computer power required for solution becomes excessive as the frequency of interest decreases. This paper shows how cavities of any length may be represented by stepped impedance cavities which, for the t.l.m. method, are only two mesh lengths long for 2-dimensional analysis and 2.5 mesh lengths long for 3-dimensional analysis. The savings in computer time and storage, using the stepped impedance technique, may be of the order of 100 times.

Erratum: Transmission-line matrix analysis of continuous waveguiding Structures using Stepped-impedance cavities

Erratum: Transmission-line matrix analysis of continuous waveguiding Structures using Stepped-impedance cavities