nport.tline — Transmission lines

A distinction is made between simple two-conductor transmission lines and multiconductor transmission lines. The latter can be analyzed in terms of propagating modes.

Two-conductor transmission lines

class nport.tline.TransmissionLine(freqs, reciprocal=False)

The RLGC parameters are calculated from the propagation constant and characteristic impedance as detailed in [EIS92].

Multi-conductor transmission lines

Todo

complete class interface and documentation

class nport.tline.MulticonductorTransmissionLine(twonport, length, reciprocal=True)

Class representing a multiconductor transmission line. It calculates:

• per-unit-length matrices (R, L, G, C),
• modal propagation constant matrices and characteristic impedance matrices, and
• natural propagation constant matrices and characteristic impedance matrices

For non-uniform lines, the characteristic impedance matrices differ for forward and backward propagation:

• modal_z0_forward and natural_z0_forward
• modal_z0_backward and natural_z0_backward

For reciprocal lines, the propagation constant matrices are the same for forward and backward propagation, while for non-reciprocal lines they differ.

Parameters:

• twonport (TwoNPort) – 2n-port that represents a multiconductor transmission line
• length (float) – physical length of the transmission line in meters
• reciprocal (bool) – True if twonport represents a reciprocal line

cpm_forward

Capacitance per meter for forward traveling waves

gamma_forward

Forward propagation constant

gpm_forward

Conductance per meter for forward traveling waves

lpm_forward

Inductance per meter for forward traveling waves

rpm_forward

Resistance per meter for forward traveling waves

z0_forward

Forward characteristic impedance

The implementation of MulticonductorTransmissionLine follows [FAR04]. An example of the application of this technique can be found in [FAR04b]. The technique was generalized in order to support non-reciprocal transmission lines.

More information on the analysis of (uniform) multiconductor transmission lines can be found in [FAR93] and [PAU08].

[EIS92]

“S-Parameter-Based IC Interconnect Transmission Line Characterization” by William R. Eisenstadt and Yungseon Eo in IEEE Transactions on Components, Hybrids, and Manufacturing Technology, vol. 15, no. 4, pp.483-490, 1992

[FAR04]

“A new generalized modal analysis theory for nonuniform multiconductor transmission lines” by J.A. Brandao Faria, in IEEE Transactions on Power Systems, vol. 19, no. 2, pp.926-933, 2004

[FAR04b]

“A New Modal Analysis Theory for Multiconductor Nonuniform Transmission-Line Structures: Application to the Analysis of Line Junctions” by J.A. Brandao Faria, in IEEE Transactions on Power Systems, vol. 19, no. 3, pp.1380-1386, 2004

[FAR93]

“Multiconductor Transmission-Line Structures - Modal Analysis Techniques” by J.A. Brandao Faria, Wiley-Interscience, 1993

[PAU08]

“Analysis of Multiconductor Transmission Lines”, 2nd edition by Clayton R. Paul Wiley-IEEE, 2008