Study On The Crosstalk Model Of Cable Bundle Based On The Multi-conductor Transmission Line Theory

As a goal of smaller size,lower weight and more functional,electronic equipments lessen their electromagnetic space much,and raise their frequency spectrums much,which leaves more serious problems of crosstalk radio interference and signal non-integrity.Crosstalks in the cable bundles,which are a main medium transmitting the diverse spectrum signals,was one of the severest electromagnetic interference of a system,and was very important in the system's electromagnetic compatibility.Multi-conductor transmission line theory was a circuit method derived by the field methods fits the study on the crosstalk in the cable bundle very much,and was easy in mixing with other methods.Therefore,the theoretical study and simulation was based on the multi-conductor transmission line theory,using the chain-parameter method in solving the problems in the frequency-domain,and using the finite-difference time domain method in solving the problems in time-domain.The main contents are as following:1.The solving method on the distributed parameters and the influencing factors of the parameters are discussed in the paper.The key point of the study is the skin effect of the internal resistors & internal inductors.Besides that,the formula of the chain parameter method was given.2.Based on the classical finite-difference time-domain method,target to the complex dielectric conformal problem,a new method using the electric field numerical weight is proposed to process the inhomogeneous cells.The iteration structure in using the finite-difference method in the multi-conductor transmission line area is analyzed,and the boundary condition in order to simulate the terminal loads was studied,and finite-difference time-domain result in the multi-conductor transmission line problems,which are a problem in single-frequency,problems in step signal of time domain and a problem of a trapezoidal pulse,are showed in this paper.3.The structures of the two-point abrupt exchanging model and the discrete rotation model of the widely used twist-wire pair bundle are stated.An improvement of the exchanging model is stated to match the condition while twisting with a reference cable.An approximation method with little error is presented,together with separating the twist wirespair into common and differential modes are presented so as to reduce the storage and time cost in the simulation.In the discrete rotation model part,the discrete model using the finite-difference time-domain is set.All the contents mentioned above have been simulated in the paper.4.The way of dealing with 3 common problems in non-uniform wiring harness area are discussed in the paper.The recursion variable method based on the Prony approximation is given to solve the problem caused by the internal impedance.A solution of the distributed capacitance in the problems caused by complex dielectric constants are presented using the electric field numerical weight in conforming which is proposed before to increase accuracy of the finite difference method's result in analyzing the complex dielectric.The problems caused by non-uniform distributed parameters are discussed by a simulation of a model whose radius has a linear dependent with the distance.