Multiconductor Transmission Lines Structure Research Articles

An efficient modeling approach of 1D-planar metamaterials in the high-frequency regime

PurposeThe purpose of this paper is to present an alternative modeling approach in terms of the determination of a physically equivalent circuit model for one-dimensional (1D) planar metamaterials in the high-frequency regime, without a postprocessing optimization procedure. Thereby, an efficient implementation of physical relationships is aimed.Design/methodology/approachIn this paper, a method based on quasi-stationary simulations and mathematical conversions to derive the values for a physically equivalent circuit model is proposed. Because the electromagnetic coupling mechanisms are investigated in detail, a simplification for the considered multiconductor transmission line structure is achieved.FindingsThe results show that the proposed modeling approach is an efficient and physically meaningful alternative to classical full-wave simulation techniques for the investigated inhomogeneous transmission line structure in both the time domain as well as in the frequency domain. In the course of this, the effort is reduced while a comparable accuracy is maintained, whereby specific coupling mechanisms are considered in circuit simulations.Originality/valueThe process to obtain information about physically interpretable lumped element values for a given structure or to determine a layout for known ones is simplified with the aid of the proposed approach. An advantageous adaption of the presented procedure to other areas of application is well conceivable.

Multiconductor Transmission Line Model for an Antenna With High-Impedance Ground Plane

We present a circuit model for an antenna above a 2-D high-impedance surface (HIS) ground plane with an arbitrary number of rows. Multiconductor transmission lines model coupling in the joint antenna and HIS structure. Discontinuities are modeled as circuit elements using closed-form expressions. One 2-D electromagnetic simulation is used to extract the per-unit-length capacitance parameters of the multiconductor transmission line structure. Input impedance predicted by the transmission line model agrees with full-wave simulations from low frequencies to above the second series resonance of the structure. The rms error in predicted $S_{11}$ of two example structures with respect to HFSS simulation is reduced by a factor of more than 2.5 compared to our previous work.

A Crosstalk Reduction Technique for Microstrip MTL Using Mode Velocity Equalization

This paper proposes a simple method to enhance the timing margin of high-speed digital signals for multiconductor transmission lines (MTLs) in inhomogeneous media. It uses interline capacitances to implement the capacitance matrix homogenizing the original inhomogeneous structure. As a result, it equalizes the velocities of all the modes involved in the MTL structure simultaneously. The design equations are derived and the limitation of the proposed scheme is explained. For the experiment, a 100-mm three-line coupled microstrip MTL (M-MTL) is built. The measured total peak-to-peak jitter including crosstalk and other noises was 91 ps in the test structure. When the M-MTL is loaded by the proposed values of lumped capacitors between the adjacent lines, the jitter is reduced to 12 ps, whereas the measurement using the even/odd mode approach shows 22 ps jitter. All the measurement results are in good agreement with the theoretical values, which proves the effectiveness of the proposed method.

Loss Angle and Permittivity Determination of a Dielectric Rod Using a Three-Wire Cage-Shape System

A simple innovative measurement system is proposed for the simultaneous determination of the loss angle and permittivity of a cylindrical dielectric rod at high-frequency regimes (megahertz band). The measurement method, based on multiconductor transmission-line (MTL) theory, explores the frequency-domain resonant features of the new proposed structure, which consists of three equally spaced wires where the cylindrical rod is tightly caged inside. The wires are bonded together at the far end of the MTL structure, while at the sending end, only two are bonded. The input impedance of the transmission line is measured against the frequency, with sharp peaks being observed when the length of the structure comes close to an odd multiple of a quarter wavelength. A theory is developed showing how the propagation parameters of the MTL device depend on the dielectric rod properties, and based on that, a measuring technique is devised for retrieving the loss angle and permittivity of the rod from the critical resonance frequencies and input impedance maximum values. Experimental results are presented to show the effectiveness of the method.

Effect of external electromagnetic waves on a confocal elliptical multiconductor transmission line structure

The influence of external electromagnetic waves on a new kind of transmission line called a confocal elliptical multiconductor transmission line structure is introduced. The capacitance and inductance matrices are obtained to attain transmission line equations. Then a uniform plane wave, TEz or TMz mode, is applied to the structure (normal incidence) to find the induced voltages and currents along the conductors using Bernardi's method. Finally, the results of this analytical method are verified using the fullwave analysis software.

Application of a harmonic expansion method approach to the computation of L and C matrices for open-boundary inhomogeneous multiconductor transmission-line structures with strong proximity effects present

A harmonic expansion method is utilised to determine the capacitance and inductance parameters of a few multiconductor transmission-line (MTL) structures comprising a set of dielectric-coated conductors in close contact seated on a ground plane. Results are presented in tabular form in order to provide microwave software developers with useful data for benchmarking purposes. In addition, an analysis of the effective permittivity characterizing the normal modes of the inhomogeneous MTL structures is presented.

Accurate Calculation of Magnetic-Field Intensity Due to Overhead Power Lines With or Without Mitigation Loops With or Without Capacitor Compensation

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> An accurate method for the evaluation of 50-Hz magnetic fields produced by overhead power lines is presented. The method, which is based on the matrix formalism of multiconductor transmission lines (MTL), allows for a correct evaluation of all the currents flowing in the MTL structure, including the currents in the subconductors of each phase bundle, the currents in the ground wires, the currents in the mitigation loop (if present), and also the earth return currents. Furthermore, the analysis also incorporates the nonuniform character of the structure arising from conductor sagging between towers. Frequency domain magnetic field calculations are performed by vectorial sum of the magnetic effects originated by all the existing currents. For exemplification purposes the case of an actual 400-kV–1.4-GVA single-circuit three-phase line is examined. Results presented include a discussion on the effects of mitigation loops with or without capacitor compensation. </para>

A New Generalized Modal Analysis Theory for Nonuniform Multiconductor Transmission Lines

Modal analysis theory plays a key role in the study of multiconductor transmission-line structures. Yet, with a few exceptions, the scope of application of the modal theory has been mainly focused on uniform line structures. However, in a very recent work by Semlyen, a new development suited for the analysis of nonuniform line structures has been presented. Such a work triggered the present paper, where a complementary generalized theory based on ABCD matrix analysis is developed encompassing both uniform and nonuniform transmission lines. A detailed study, using matrix methods, is presented, showing how modal decoupling of transmission line equations can be achieved in the general case of multiconductor nonuniform structures. Appropriate coordinate transformations are introduced. Wave propagation parameters (modal propagation constants and forward- and backward-modal surge admittances) are defined.

Conservation laws for time-domain signals propagating along multiconductor transmission-line structures

Conservation laws for time-domain signals propagating along general multiconductor transmission-line structures are derived. Conservation of voltage-pulse areas and current-pulse areas are obtained from fundamental principles based directly on Maxwell&apos;s equations. Underlying assumptions are described and discussed.

Radiation from Multiconductor Transmission Lines: Exact Time-Domain Analysis

An exact expression for the radiated EM fields due to a multiconductor transmission line structure with a wire or ground plane as a return path has been presented. First the coupled equations describing the system have been decomposed to find the current along the lines, and then a time-domain approach has been presented to derive the radiated fields. It has been shown that the radiated field can be expressed as a function of the voltages and currents in the terminals.

Diagnosing transmission line termination faults by means of wavelet based crosstalk signature recognition

This paper describes a technique that allows one to identify the faulty condition (open or short circuit) at a termination of a multiconductor transmission line structure by measuring the induced voltage at the other end. The wavelet theory is used to filter out from the signal the components due to unwanted sources, and to decompose it to obtain the fault's signature. The comparison (or matching) algorithm is substituted by an artificial neural network. Two differently designed neural networks are used to validate the results and the overall procedure is also tested on an experimental set-up.

Edge effect enforced boundary element analysis of multilayered transmission lines

An improved boundary element method (BEM) for the calculation of the capacitance matrix in a multiconductor transmission line structure is presented, where the edge singularities of the charge and current near the corners of the cross-sections of the signal lines are embedded in the basis functions. The new method demonstrates improved accuracy and enhanced computational efficiency in comparison to previous methods. The results for the new algorithm are compared with those for other approaches presented in the literature.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>