Multi-conductor Transmission Line Method Research Articles

Lightning analysis of adjacent grounding systems using multi-conductor transmission line method

The analysis of adjacent grounding systems under lightning currents which is responsible for many safety problems to human beings and damages to devices is very important. In this study, the behaviours of such grounding grids under lightning conditions which are not well documented in the literature are analysed using the multi-conductor transmission line method in a two-layer soil model. To achieve this goal, the expressions related to the study of a single grounding grid extracted from the recent study of the authors are developed to be appropriate to the analysis of adjacent grounding systems under lightning currents. Also, through the representation of the connectivity matrix, the analysis of the adjacent grounding grids with any size and degree of complexity is facilitated. Furthermore, the behaviours of the adjacent grounding grids under different lightning and soil characteristics are examined and some conclusions are derived.

Efficient Analytical Model for the Transfer Impedance and Admittance of Noncoaxial/Twinax Braided–Shielded Cables

An efficient analytical model for the transfer impedance and admittance of a noncoaxial/twinax braided–shielded cable with apertures on its sheath is proposed by generalizing the old Vance's and Kley's formulas, and it is derived using the complex analyses with an appropriate conformal mapping. Therefore, such a noncoaxial cable is converted into a coaxial one which can be studied using the traditional multiconductor transmission line method. It is shown that the aperture inductance is related to the position of the inner conductor and the radial position of each aperture on its sheath. In addition, the modal domain analysis is performed to obtain the common-mode (CM) and differential-mode (DM) transfer impedance/admittance of the twinax braided–shielded cable, with CM and DM currents inside the inner conductors examined. The proposed model is validated by comparing the results with that obtained by the method of moments (MoM)-based commercial software FEKO. It is found that the uniform distribution of the apertures on the sheath reduces the induced DM current significantly

Frequency Domain Analysis of EM Crosstalk Problem in a Quad by the Equivalent Cable Bundle Method Among Twisted-Wire Pairs Cable Bundle

In this paper, the equivalent cable bundle method (ECBM) is used with some modifications to predict crosstalk within a bundle of twisted-wire pairs (TWPs) terminating with differential loads at their far end and colocalized as quads in the frequency domain. When using this method, one can easily calculate crosstalk in many pairs with good reduction of complexity and computation time. In this paper, power loss of crosstalk is calculated for both complete and reduced models using the multiconductor transmission lines method. It is shown that the results are in agreement by applying this modified ECBM, and the number of wires as well as the computation time is successfully reduced. The in-quad is the four conductors located in the same quad and the outside-quad is all other conductors in the bundle. The in-quad and outside-quad architecture results are also discussed, and it is observed that the in-quad crosstalk has an enormous amount of crosstalk compared with the outside-quad crosstalk. A new three-step ECBM for predicting the crosstalk within a TWP network is proposed, the pairs are colocalized as quads, and the use of this method allows an easy modeling of crosstalk within a TWP cable bundle.

Dispersion characteristics of the coaxial interlaced disk-loaded waveguide slow-wave structure

The dispersion equation of the coaxial interlaced disk-loaded waveguide slow-wave structure is derived by the multi-conductor transmission line method. The simulation results by HFSS are in good agreement with the calculation results obtained from the dispersion equation. Influences of structure parameters on dispersion characteristics are discussed. It can be concluded that with the increase of inner conductor and the decrease of the period length, the bandwidth of the slow-wave structure becomes greater. The dispersion characteristics of the coaxial interlaced disk-loaded waveguide and those of the coaxial disk-loaded waveguide are compared. The results show that the coaxial interlaced disk-loaded structure can obtain a wide bandwidth and weak dispersion. This study will be a guide to the research of the coaxial interlaced disk-loaded waveguide slow wave structure used in the traveling-wave tube.

MTL-Based Analysis to Distinguish High-Frequency Behavior of Interleaved Windings in Power Transformers

An elaborate method to analyze the high-frequency behavior of transformer windings by means of the multiconductor transmission line (MTL) method is presented. A procedure for the evaluation of per-unit length parameters for transformer windings (TWs) is enumerated, which is not available in existing literature on the subject. A full-length detailed solution of the MTL method for TW is also demonstrated. A comparison of this method with the conventional circuit approach is illustrated wherever necessary. The analysis of two types of commonly used interleaved windings is performed in this paper. It is also inferred from experimental results that a conventional low-voltage impulse test is insufficient to make a distinction between the two windings. As far as interwinding oscillations at high-frequency excitations are concerned, it also proved by the MTL analysis that one type is better than the other.