## Equivalent Circuit of a Long Line:

So far as the end conditions are concerned, the Equivalent Circuit of a Long Line can be established in the form of a T- or π-network.

The parameters of the equivalent network are easily obtained by comparing the performance equations of a π-network and a transmission line in terms of end quantities. For a π-network shown in Fig. 5.15. According to exact solution of a long line For exact equivalence, we must have From Eq. (5.50)

is the factor by which the series impedance of the nominal-π must be multiplied to obtain the Z’ parameter of the equivalent-π, Substituting Z’ from Eq. (5.50) in Eq. (5.51), we get is the factor by which the shunt admittance arm of the nominal- π must be multiplied to obtain the shunt parameter ( Y’/2) of the equivalent- π.

is a consistent equation in terms of the above values of Y’ and Z’.

For a line of medium length so that the equivalent- π network reduces to that of nominal- π. Equivalent-T network parameters of a transmission line are obtained on similar lines. The equivalent-T network is shown in Fig. 5.16.