Equivalent distributed Circuit

We can easily symbolized TEM mode in a transmission line by the equivalent circuit, shown in dia4.7 below, for a length Az. Physically, it is said to be  distributed circuit because the circuit parts are not lumped at separate locations as in a conventional low-frequency circuit rather they are distributed uniformly along the length of the line. Thus, we can define the elements on per-unit-length basis.

The series resistance per unit length, R, is the resultant resistance of all the conductors connected in the line,& it accounts for power indulgence in the conductors. As current flow along the conductor's surface is accompanied by a circumferential magnetic field.

The connection between magnetic flux with the current produces a combined inductance per unit length, L, which takes in into account the flux linkages both internal and external to the conductors. Positive and negative charges of equal magnitude are implimented on the 2 conductors.

This charge separation produces a potential b/w between the conductors, which accounts for the capacitance per unit length, C. The shunt conductance per unit length, G, accounts for the power dissipation in the non-ideal dielectric medium b/w the conductors.

Use of Kirchhoff's voltage and current laws to the circuit path to the system of coupled differential equations for the phasor voltage & current in the limit