CN103226166B - Computational method of transfer characteristic of shielded twisted pair RLCG - Google Patents

Abstract

The invention discloses a shielded twisted pair RLCG model and a computational method of a transfer characteristic thereof. A shielded layer of a shielded twisted pair is regarded as a third conductor and the third conductor is regarded as a reference of two leads in the shielded layer. The whole shielded twisted pair has three conductors; the RLCG parameter is distributed on a small segment length dz on the shielded twisted pair and is equivalent to the RLCG parameter model; a form of an RLCG parameter matrix is set according to the shielded twisted pair model; a resistance R matrix, an inductance L matrix, a capacitance C matrix and a conductance G matrix are calculated respectively; and a transmission constant matrix and a characteristic impedance matrix of the shielded twisted pair are calculated according to all the matrices, so that voltage/ current relationship at the discretional position and the source position on the shielded twisted pair, namely the characteristic impedance matrix of the shielded twisted pair is obtained. According to the shielded twisted pair RLCG model and the computational method of the transfer characteristic thereof, a data source is an inherent material parameter of the shielded twisted pair, so that fussy measurement and an introduced measuring error due to the fussy measurement are avoided.

Description

A kind of computational methods of Shielded Twisted Pair transmission characteristic

Technical field

The present invention relates to a kind of Shielded Twisted Pair.Particularly relate to a kind of computational methods of the Shielded Twisted Pair transmission characteristic for 1553B Shielded Twisted Pair.

Background technology

The transmission of the signal of telecommunication is one of main Signal transmissions form, and the access of current airborne high-speed data signal is mainly based on the digital time-multiplex data transmission technology in 1553B bus system.This is because the design of early stage air environment and installation cover a wide range, the comprehensive method of investment cannot be estimated, make full use of existing 1553B bus system to provide new high-speed data access service, not only investment can be reduced, and be convenient to the continuity of mature technology and expansion (see Dennis J.Rauschmayer, Yang Wei, ADSL/VDSL principle, People's Telecon Publishing House, 2001.ISBN 7-115-09153-6/TP2108).Simultaneously, early stage Successful utilization on military airborne equipment, 1553B bus is made to have carried out promoting widely on the military platforms such as airborne/missile-borne/carrier-borne integrated fire control system, artificial satellite, for the utilization carrier that these are different, need to carry out Accurate Prediction to the transmission characteristic of channel in the design process flexibly, easily, thus guarantee data transmission quality (see: seek the modeling and simulation [D] building sunshine .1553B bus system. Xian Electronics Science and Technology University 2011).In addition, new application needs higher bandwidth resources, be applicable to the development of long distance, jumbo optical fiber communication, higher rate requirement is proposed to the 1553B bus system based on Shielded Twisted Pair, and also needs to be well understood to the characteristic of channel for the problem such as the multipath run into, crosstalk solved in channel dilation process.Visible, realizing the flexible design of 1553B bus system and utilization, completing the lifting of whole bus system data rate, all in the urgent need to describing exactly the channel transfer characteristic of 1553B bus system.

Shielded Twisted Pair is the important component part of 1553B bus system, the analytical method of its transmission characteristic has a variety of, as being applied in W-element modelling in HSPICE and TLM method (Transmission Lines Matrix) method (see T.Starr, J.M.Cioffi and P.J.Silverman, Understanding Digital Subscriber Line Technology [M], PrenticeHall, Upper Saddle River, NJ, 1999).The RLCG parametric method herein introduced is the transmission characteristic describing unit length Shielded Twisted Pair with the distributed constant matrix of resistance R, inductance L, electric capacity C, conductance G and telegraph equation.

Summary of the invention

Technical problem to be solved by this invention is, a kind of structural parameters known by 1553B Shielded Twisted Pair and material behavior are provided, just the RLCG parameter of transmission line can be obtained, and obtain the transmission characteristic of Shielded Twisted Pair exactly, and then provide the computational methods of Shielded Twisted Pair transmission characteristic of Shielded Twisted Pair channel model.

The technical solution adopted in the present invention is: a kind of computational methods of Shielded Twisted Pair transmission characteristic, comprise the steps:

1) according to the form of Shielded Twisted Pair RLCG model specification RLCG parameter matrix:

$R=\left[\begin{array}{cc}{R}_0+R_1& R_0\\ R_0& R_0+R_2\end{array}\right]=\left[\begin{array}{cc}{R}_1& 0\\ 0& R_2\end{array}\right]+\left[\begin{array}{cc}{R}_0& R_0\\ R_0& R_0\end{array}\right]$

$L=\left[\begin{array}{cc}{L}_{11}& L_{12}\\ L_{12}& L_{22}\end{array}\right]$

$C=\left[\begin{array}{cc}{C}_{11}+C_{12}& -C_{12}\\ -C_{12}& C_{22}+C_{12}\end{array}\right]$

$G=\left[\begin{array}{cc}{G}_{11}+G_{12}& -G_{12}\\ -G_{12}& G_{22}+G_{12}\end{array}\right]$

In formula, R ₀for the D.C. resistance of screen unit length, R ₁and R ₂be respectively the D.C. resistance of two conductor unit length, have R for 1553B Shielded Twisted Pair ₁=R ₂; L ₁₁and L ₂₂be respectively two mutual inductances between conductor and screen, and L ₁₁=L ₂₂, L ₁₂it is the mutual inductance between two conductors; In like manner, C ₁₁, G ₁₁with C ₂₂, G ₂₂be respectively two electric capacity between conductor and screen and conductance, C ₁₂with G ₁₂be the electric capacity between two conductors and conductance, these parameters are all the material behavior of Shielded Twisted Pair and the function of structural parameters;

2) according to material electrical quantity and size, each element value of spatial distributed parameters calculating RLCG parameter matrix of Shielded Twisted Pair each several part;

3) according to step 2) the transmission matrix γ of RLCG parameter value calculation Shielded Twisted Pair that obtains and the characteristic impedance matrix Z of Shielded Twisted Pair ₀, wherein:

$\mathrm{\γ}=\mathrm{\α}+\mathrm{j\β}=\sqrt{(R+\mathrm{j\ωL})(G+\mathrm{j\ωC})};Z_0=\sqrt{\frac{R+\mathrm{j\ωL}}{G+\mathrm{j\ωC}}}$

In formula, ω is the angular frequency of input signal, and j is imaginary unit;

4) according to step 3) the transmission matrix γ of Shielded Twisted Pair, the characteristic impedance matrix Z of Shielded Twisted Pair that obtain ₀and Kirchhoff's law, obtaining the voltage/current relation at any position and source position place in Shielded Twisted Pair, is also the transmission characteristic matrix T of Shielded Twisted Pair:

T＝[cosh(γ ^Tdx)+sinh(γ ^Tdx)Y _tZ ₀] ^-1

Corresponding transmission matrix Φ:

$\mathrm{\Φ}=\left[\begin{array}{cc}\cosh \left(\mathrm{\γdx}\right)& \sinh \left(\mathrm{\γdx}\right)Z_0\\ \sinh \left({\mathrm{\γ}}^h\mathrm{dx}\right){Z_0}^{-1}& \cosh \left({\mathrm{\γ}}^T\mathrm{dx}\right)\end{array}\right]$

In formula, sinh is hyperbolic sine function, and cosh is hyperbolic cosine function, γ ^tthe transposed matrix of Shielded Twisted Pair transmission matrix γ, Z ₀ ^-1shielded Twisted Pair characteristic impedance matrix Z ₀inverse matrix, Y _tit is the susceptance matrix of known load.

Step 2) described in calculating RLCG parameter matrix in resistance R matrix in each element parameter value be:

(1) calculate the skin depth δ of copper conductor, unit is rice:

$\mathrm{\δ}=\frac{1}{\sqrt{\mathrm{\πf\μ}{\mathrm{\σ}}_{\mathrm{Cu}}}}$

In formula, σ _cube the conductivity of metallic copper, unit is Siemens/rice; F is the frequency of input signal, and unit is hertz; μ is the dielectric constant of metallic copper, and unit is farad/rice;

(2) obtained by (1) calculate the D.C. resistance R in u root copper conductor unit length _uvalue, be also resistivity, unit is ohm/meter:

In formula, σ _cube the conductivity of metallic copper, unit is Siemens/rice; r _wit is the radius of copper conductor;

(3) R being positioned at u capable v row place element in resistor matrix R is obtained _u,vvalue, unit is ohm/meter:

u, v appoint and get 1 or 2

In formula, R ₀be the D.C. resistance in screen unit length, unit is ohm/meter.

Step 2) described in calculating RLCG parameter matrix in the parameter value of each element of inductance L matrix be: one by one mirror image analysis is carried out to copper conductor, draws in inductance matrix L the value L being positioned at u capable v row place element _u,v, unit is Henry/rice:

In formula,

R _sfor the radius of screen, d _ufor the distance that label is between the u root copper conductor of u and screen central point, r _wbe the radius of copper conductor, θ is the angle between u root copper conductor and v root copper conductor, and ε is the dielectric constant of metallic copper.

Step 2) described in calculating RLCG parameter matrix in electric capacity C matrix be:

C＝εξL ^-1

In formula, ε is the dielectric constant of metallic copper; ξ is the magnetic permeability of metallic copper, and unit is Henry/rice; L is inductance matrix, can obtain capacitance matrix C, and in matrix, the unit of each element is farad/rice.

Step 2) described in calculating RLCG parameter matrix in conductance G matrix be:

$G=\frac{{{\mathrm{\σ}}_c}_u}{\mathrm{\ξ}}C$

In formula, C is the parameter matrix of electric capacity, σ _cuit is the conductivity of metallic copper; ξ is the magnetic permeability of metallic copper; In matrix, the unit of each element is Siemens/rice.

The computational methods of a kind of Shielded Twisted Pair transmission characteristic of the present invention, compared with obtaining the transmission characteristic of Shielded Twisted Pair with the general method by surveying, data source is the intrinsic material parameter of Shielded Twisted Pair, the measure error avoiding loaded down with trivial details measurement and introduce thus.Meanwhile, the present invention is based on strict theory deduction, compare with measurement method with empirical estimation method, its conclusion has mathematics and physical significance, and is convenient to carry out further theoretical research and popularization on the basis of result of the present invention.

By the transmission characteristic of the Shielded Twisted Pair represented by RLCG parameter, the reliability of the Shielded Twisted Pair transmission when signal to be transmitted is known can be predicted, signal distortion degree in prediction Shielded Twisted Pair between arbitrary node, and instruct the design of whole 1553B high-speed data system accordingly, avoid producing disabled terminal node, thus improve the performance of whole system.Meanwhile, the method has certain reference and reference value to the theoretical research of other similar wired high speed transmission systems and realization.

Accompanying drawing explanation

Fig. 1 is the structural representation of 1553B Shielded Twisted Pair;

Fig. 2 is the equivalent RLCG parameter model of Shielded Twisted Pair;

Fig. 3 is the structural representation of Shielded Twisted Pair mirror image analytic approach.

In figure

1: sheath 2: screen

3: insulating case 4: copper conductor

5: filler 41: the first copper conductors

42: the second copper conductors

Embodiment

Below in conjunction with embodiment and accompanying drawing, the computational methods to a kind of Shielded Twisted Pair transmission characteristic of the present invention are described in detail.

Use the Shielded Twisted Pair of standard in 1553B system, as shown in Figure 1, in its transmission direction, the structure in any cross section is all identical, can think that its distributed constant is not evenly and with change in location.The screen 2 of Shielded Twisted Pair is regarded as the 3rd conductor, and it can be used as the reference of two copper conductors 4 in screen.Then whole Shielded Twisted Pair has three conductors, in Shielded Twisted Pair, the RLCG parameter distribution of a bit of length dx as shown in Figure 2, namely Shielded Twisted Pair RLCG model of the present invention comprises: first copper conductor, 41, second copper conductor 42 and screen 2, first described copper conductor 41 is serially connected with resistance R successively ₁dx and inductance L ₁₁dx, second described copper conductor 42 is serially connected with resistance R successively ₂dx and inductance L ₂₂dx, described screen 2 has resistance R ₀dx, is connected with inductance L between first copper conductor 41 and second copper conductor 42 ₁₂dx, is connected to electric capacity C between first copper conductor 41 and second copper conductor 42 ₁₂dx and conductance G ₁₂dx, is connected to electric capacity C between first copper conductor 41 and screen 2 ₁₁dx and conductance G ₁₁dx, is connected to electric capacity C between second copper conductor 42 and screen 2 ₂₂dx and conductance G ₂₂dx, wherein, the input current of first described copper conductor 41 is I ₁x (), input voltage is V ₁x (), output current is I ₁(x+dx), output voltage is V ₁(x+dx); The input current of second described copper conductor 42 is I ₂x (), input voltage is V ₂x (), output current is I ₂(x+dx), output voltage is V ₂(x+dx); The input current of described screen 2 is output current is

Utilize the equivalent RLCG parameter model shown in Fig. 2, to obtain the computational methods of the Shielded Twisted Pair transmission characteristic based on Shielded Twisted Pair RLCG model of the present invention, comprise the steps:

1) according to the form of Shielded Twisted Pair RLCG model specification RLCG parameter matrix, because twisted-pair feeder and screen are considered as three conductors by model, then each parameter of RLCG is the matrix of 2 × 2:

$R=\left[\begin{array}{cc}{R}_0+R_1& R_0\\ R_0& R_0+R_2\end{array}\right]=\left[\begin{array}{cc}{R}_1& 0\\ 0& R_2\end{array}\right]+\left[\begin{array}{cc}{R}_0& R_0\\ R_0& R_0\end{array}\right]$

$L=\left[\begin{array}{cc}{L}_{11}& L_{12}\\ L_{12}& L_{22}\end{array}\right]$ $C=\left[\begin{array}{cc}{C}_{11}+C_{12}& -C_{12}\\ -C_{12}& C_{22}+C_{12}\end{array}\right]$

$G=\left[\begin{array}{cc}{G}_{11}+G_{12}& -G_{12}\\ -G_{12}& G_{22}+G_{12}\end{array}\right]$

In formula, R ₀for the D.C. resistance of screen unit length, R ₁and R ₂be respectively the D.C. resistance of two conductor unit length, have R for 1553B Shielded Twisted Pair ₁=R ₂; L ₁₁and L ₂₂be respectively two mutual inductances between conductor and screen, and L ₁₁=L ₂₂, L ₁₂it is the mutual inductance between two conductors; In like manner, C ₁₁, G ₁₁with C ₂₂, G ₂₂be respectively two electric capacity between conductor and screen and conductance, C ₁₂with G ₁₂be the electric capacity between two conductors and conductance, these parameters are all the material behavior of Shielded Twisted Pair and the function of structural parameters;

Thus the RLCG parameter of unit length Shielded Twisted Pair can describe by the parameter matrix form in above formula.

2) according to material electrical quantity and size, each element value of spatial distributed parameters calculating RLCG parameter matrix of Shielded Twisted Pair each several part, be calculate resistance R matrix, inductance L matrix, electric capacity C matrix and conductance G matrix respectively, comprise:

(1) each element parameter value calculated in the resistance R matrix in RLCG parameter matrix is:

A () calculates the skin depth δ of copper conductor, unit is rice:

$\mathrm{\δ}=\frac{1}{\sqrt{\mathrm{\πf\μ}{\mathrm{\σ}}_{\mathrm{Cu}}}}$

In formula, σ _cube the conductivity of metallic copper, unit is Siemens/rice; F is the frequency of input signal, and unit is hertz; μ is the dielectric constant of metallic copper, and unit is farad/rice;

B () is obtained by (a) calculate the D.C. resistance R in u root copper conductor unit length _uvalue, be also resistivity, unit is ohm/meter:

In formula, σ _cube the conductivity of metallic copper, unit is Siemens/rice; r _wit is the radius of copper conductor;

C () obtains the R being positioned at u capable v row place element in resistor matrix R _u,vvalue, unit is ohm/meter:

u, v appoint and get 1 or 2

In formula, R ₀be the D.C. resistance in screen unit length, unit is ohm/meter.

(2) parameter value calculating each element of inductance L matrix in RLCG parameter matrix is:

The each element in inductance matrix L can be calculated by the cross section parameters of transmission line according to image method.As shown in Figure 3, the mirror image of every root copper conductor is placed on outside screen, and corresponding with its native copper wire.During for making mirror image, two conductors act under desirable Mirroring Environment, ensure that screen is equipotential plane, therefore think that the impedance of screen can be ignored.The electric current of mirror image copper conductor is equal with the size of current in native copper wire, direction is contrary.On the arbitrary cross section of twisted-pair feeder, the center three of the center of mirror image copper conductor, the center of native copper wire, screen is in alignment.R _sfor the radius of screen, d _ufor the distance that label is between the u root copper conductor of u and screen central point, then the distance of mirror image copper conductor central point and screen central point is r _s ²/ d _u.R _wbe the radius of copper conductor, θ is the angle between u root copper conductor and v root copper conductor.One by one mirror image analysis is carried out to copper conductor, draws in inductance matrix L the value L being positioned at u capable v row place element _u,v, unit is Henry/rice:

(3) calculate electric capacity C matrix in RLCG parameter matrix, be by inductance matrix L, capacitance matrix C can be obtained as follows:

C＝μξL ^-1

In formula, μ is the dielectric constant of metallic copper; ξ is the magnetic permeability of metallic copper, and unit is Henry/rice; L is inductance matrix, can obtain capacitance matrix C, and in matrix, the unit of each element is farad/rice.

(4) calculate conductance G matrix in RLCG parameter matrix, be by capacitance matrix C, conductance matrix G can be obtained:

$G=\frac{{{\mathrm{\σ}}_c}_u}{\mathrm{\ξ}}C$

In formula, C is the parameter matrix of electric capacity, σ _cuit is the conductivity of metallic copper; ξ is the magnetic permeability of metallic copper; In matrix, the unit of each element is Siemens/rice.

3) according to step 2) the transmission matrix γ of RLCG parameter value calculation Shielded Twisted Pair that obtains and the characteristic impedance matrix Z of Shielded Twisted Pair ₀, wherein:

$\mathrm{\γ}=\mathrm{\α}+\mathrm{j\β}=\sqrt{(R+\mathrm{j\ωL})(G+\mathrm{j\ωC})};Z_0=\sqrt{\frac{R+\mathrm{j\ωL}}{G+\mathrm{j\ωC}}}$

In formula, ω is the angular frequency of input signal, and j is imaginary unit.

4) according to step 3) the transmission matrix γ of Shielded Twisted Pair, the characteristic impedance matrix Z of Shielded Twisted Pair that obtain ₀and Kirchhoff's law, then the telegraph equation of the Shielded Twisted Pair of unit length is:

$\frac{\mathrm{dV}(x,t)}{\mathrm{dx}}\mathrm{RI}(x,t)+L\frac{\mathrm{dI}(x,t)}{\mathrm{dt}}$

$\frac{\mathrm{dI}(x,t)}{\mathrm{dx}}\mathrm{GI}(x,t)+C\frac{\mathrm{dV}(x,t)}{\mathrm{dt}}$

Wherein,

$V(x,t)=\left[\begin{array}{c}{V}_1(x,t)\\ V_2(x,t)\end{array}\right]$

$I(x,t)=\left[\begin{array}{c}{I}_1(x,t)\\ I_2(x,t)\end{array}\right]$

Due to the uniform transmission line that 1553B Shielded Twisted Pair is symmetrical, time humorous field time, above-mentioned two formulas can be abbreviated as:

$\frac{d^{2}V}{{\mathrm{dx}}^2}={\mathrm{\γ}}^{2}V$

$\frac{d^{2}I}{{\mathrm{dx}}^2}={\mathrm{\γ}}^{2}I$

Wherein,

$\mathrm{\γ}=\mathrm{\α}+\mathrm{j\β}=\sqrt{(R+\mathrm{j\ωL})(G+\mathrm{j\ωC})};Z_0=\sqrt{\frac{R+\mathrm{j\ωL}}{G+\mathrm{j\ωC}}}$

ω is the angular frequency of input signal, and j is imaginary unit.

Then solution two differential equations above, can obtain:

V(x+dx,t)＝cosh(γdx)·V(x,t)+sinh(γdx)Z ₀·I(x,t)

I(x+dx,t)＝sinh(γ ^Tdx)·Z ₀ ^-1·V(x,t)+cosh(γ ^Tdx)·I(x,t)

Being write matrix form is:

$\left[\begin{array}{c}V(x+\mathrm{dx},t)\\ I(x+\mathrm{dx},t)\end{array}\right]=\left[\begin{array}{cc}\cosh \left(\mathrm{\γdx}\right)& \sinh \left(\mathrm{\γdx}\right)Z_0\\ \sinh \left({\mathrm{\γ}}^T\mathrm{dx}\right){Z_0}^{-1}& \cosh \left({\mathrm{\γ}}^T\mathrm{dx}\right)\end{array}\right]\left[\begin{array}{c}V(x,t)\\ I(x,t)\end{array}\right]$

Then can obtain its transmission matrix Φ is:

$\mathrm{\Φ}=\left[\begin{array}{cc}\cosh \left(\mathrm{\γdx}\right)& \sinh \left(\mathrm{\γdx}\right)Z_0\\ \sinh \left({\mathrm{\γ}}^h\mathrm{dx}\right){Z_0}^{-1}& \cosh \left({\mathrm{\γ}}^T\mathrm{dx}\right)\end{array}\right]$

Thus obtain the voltage/current relation at any position and source position place in Shielded Twisted Pair, be also the transmission characteristic matrix T of Shielded Twisted Pair:

T＝[cosh(γ ^Tdx)+sinh(γ ^Tdx)Y _tZ ₀] ^-1

In formula, sinh is hyperbolic sine function, and cosh is hyperbolic cosine function, γ ^tthe transposed matrix of Shielded Twisted Pair transmission matrix γ, Z ₀ ^-1shielded Twisted Pair characteristic impedance matrix Z ₀inverse matrix, Y _tit is the susceptance matrix of known load.

Visible, the transmission characteristic matrix T (or transmission matrix Φ) of Shielded Twisted Pair can by γ and Z ₀parameter matrix is expressed, and γ and Z ₀parameter matrix can be expressed by RLCG parameter matrix.

Claims (5)

1. computational methods for Shielded Twisted Pair transmission characteristic, is characterized in that, comprise the steps:

1) according to the form of Shielded Twisted Pair RLCG model specification RLCG parameter matrix:

$R=\left[\begin{array}{cc}{R}_0+R_1& R_0\\ R_0& R_0+R_2\end{array}\right]=\left[\begin{array}{cc}{R}_1& 0\\ 0& R_2\end{array}\right]+\left[\begin{array}{cc}{R}_0& R_0\\ R_0& R_0\end{array}\right]$

$L=\left[\begin{array}{cc}{L}_{11}& L_{12}\\ L_{12}& L_{22}\end{array}\right]$

$C=\left[\begin{array}{cc}{C}_{11}+C_{12}& -C_{12}\\ -C_{12}& C_{22}+C_{12}\end{array}\right]$

$G=\left[\begin{array}{cc}{G}_{11}+G_{12}& -G_{12}\\ -G_{12}& G_{22}+G_{12}\end{array}\right]$

In formula, R ₀for the D.C. resistance of screen unit length, R ₁and R ₂be respectively the D.C. resistance of two conductor unit length, have R for 1553B Shielded Twisted Pair ₁=R ₂; L ₁₁and L ₂₂be respectively two mutual inductances between conductor and screen, and L ₁₁=L ₂₂, L ₁₂it is the mutual inductance between two conductors; In like manner, C ₁₁, G ₁₁with C ₂₂, G ₂₂be respectively two electric capacity between conductor and screen and conductance, C ₁₂with G ₁₂be the electric capacity between two conductors and conductance, these parameters are all the material behavior of Shielded Twisted Pair and the function of structural parameters;

2) according to material electrical quantity and size, each element value of spatial distributed parameters calculating RLCG parameter matrix of Shielded Twisted Pair each several part;

3) according to step 2) the transmission matrix γ of RLCG parameter value calculation Shielded Twisted Pair that obtains and the characteristic impedance matrix Z of Shielded Twisted Pair ₀, wherein:

$\mathrm{\γ}=\mathrm{\α}+\mathrm{j\β}=\sqrt{(R+\mathrm{j\ωL})(G+\mathrm{j\ωC})};$ $Z_0=\sqrt{\frac{R+\mathrm{j\ωL}}{G+\mathrm{j\ωC}}}$

In formula, ω is the angular frequency of input signal, and j is imaginary unit;

4) according to step 3) the transmission matrix γ of Shielded Twisted Pair, the characteristic impedance matrix Z of Shielded Twisted Pair that obtain ₀and Kirchhoff's law, obtaining the voltage/current relation at any position and source position place in Shielded Twisted Pair, is also the transmission characteristic matrix T of Shielded Twisted Pair:

T＝[cosh(γ ^Tdx)+sinh(γ ^Tdx)Y _tZ ₀] ^-1

Corresponding transmission matrix Φ:

$\mathrm{\Φ}=\left[\begin{array}{cc}\cosh \left(\mathrm{\γdx}\right)& \sinh \left(\mathrm{\γdx}\right)Z_0\\ \sinh \left({\mathrm{\γ}}^T\mathrm{dx}\right){Z_0}^{-1}& \cosh \left({\mathrm{\γ}}^T\mathrm{dx}\right)\end{array}\right]$

In formula, sinh is hyperbolic sine function, and cosh is hyperbolic cosine function, γ ^tthe transposed matrix of Shielded Twisted Pair transmission matrix γ, Z ₀ ^-1shielded Twisted Pair characteristic impedance matrix Z ₀inverse matrix, Y _tit is the susceptance matrix of known load.

2. the computational methods of a kind of Shielded Twisted Pair transmission characteristic according to claim 1, is characterized in that, step 2) described in calculating RLCG parameter matrix in resistance R matrix in each element parameter value be:

(1) calculate the skin depth δ of copper conductor, unit is rice:

$\mathrm{\δ}=\frac{1}{\sqrt{\mathrm{\πf\μ}{\mathrm{\σ}}_{\mathrm{Cu}}}}$

In formula, σ _cube the conductivity of metallic copper, unit is Siemens/rice; F is the frequency of input signal, and unit is hertz; μ is the dielectric constant of metallic copper, and unit is farad/rice;

(2) obtained by (1) calculate the D.C. resistance R in u root copper conductor unit length _uvalue, be also resistivity, unit is ohm/meter:

In formula, σ _cube the conductivity of metallic copper, unit is Siemens/rice; r _wit is the radius of copper conductor;

(3) R being positioned at u capable v row place element in resistor matrix R is obtained _u,vvalue, unit is ohm/meter:

In formula, R ₀be the D.C. resistance in screen unit length, unit is ohm/meter.

3. the computational methods of a kind of Shielded Twisted Pair transmission characteristic according to claim 1, it is characterized in that, step 2) described in calculating RLCG parameter matrix in the parameter value of each element of inductance L matrix be: one by one mirror image analysis is carried out to copper conductor, draws in inductance matrix L the value L being positioned at u capable v row place element _u,v, unit is Henry/rice:

In formula,

R _sfor the radius of screen, d _ufor the distance that label is between the u root copper conductor of u and screen central point, r _wbe the radius of copper conductor, θ is the angle between u root copper conductor and v root copper conductor, and ε is the dielectric constant of metallic copper.

4. the computational methods of a kind of Shielded Twisted Pair transmission characteristic according to claim 1, is characterized in that, step 2) described in calculating RLCG parameter matrix in electric capacity C matrix be:

C＝εξL ^-1

In formula, ε is the dielectric constant of metallic copper; ξ is the magnetic permeability of metallic copper, and unit is Henry/rice; L is inductance matrix, can obtain capacitance matrix C, and in matrix, the unit of each element is farad/rice.

5. the computational methods of a kind of Shielded Twisted Pair transmission characteristic according to claim 1, is characterized in that, step 2) described in calculating RLCG parameter matrix in conductance G matrix be:

$G=\frac{{\mathrm{\σ}}_{c_u}}{\mathrm{\ξ}}C$

In formula, C is the parameter matrix of electric capacity, σ _cuit is the conductivity of metallic copper; ξ is the magnetic permeability of metallic copper; In matrix, the unit of each element is Siemens/rice.