Lecture 5 : Standing Waves on Transmission Line & Impedance Transformation
General Impedance Transformation
The impedance at any point of line is a transformed version of the load impedance.
Infact there is nothing special about the load impedance. The impedance transformation can be between
any two locations on the line. It should be remembered however, that the sign convention for the distance
on the line must be correctly taken.
If the length is measured towards the generator it is taken positive.
If the length is measured away from the generator, it is taken negative.
In the figure if we go from X to Y, ' is negative and if we go from Y to X, is positive.
If the impedance at is , its transformed version at will be given by
-------- (2.3)
Inverting the relation we get,
-------- (2.4)
It can be noted that the above two expressions 2.3 and 2.4 are same expression with and interchanged and replaced by
Conclusion
Expression 2.3 is the general impedance transformation relation which can be used for transforming impedance
on one location on the line to the other. If the impedance is transformed to a point towards the generator,
is positive, and if it is transformed to a point away from the generator, is negative.
' is negative and if we go from Y to X, 
is positive. 
is 
, its transformed version at 
will be 
given by 
and 
interchanged and 
replaced by 
is positive, and if it is transformed to a point away from the generator, 
is negative. 
