Lecture 10 : Transmisssion Line Calculations Using Smith Chart
Constant VSWR Circles
The reflection coefficient at any location on the line is
Let be written in polar form as
Then we get,
Where,
and
As we move along the line towards the generator
increases and consequently,
becomes more negative. However, R remains constant.
The
point moves on a circle with centre (0,0) and radiurs R in the complex
- plane.
If we move towards the generator,
is positive and the point moves clockwise on the circle.
For movement away from the generator, the point moves anti-clockwise on the circle.
For a circle,
. Since VSWR
,
is constant for the circle.
That is, all points on the circle have same VSWR,
. This circle therefore is called the CONSTANT VSWR CIRCLE.
be written in polar form as 
increases and consequently,
becomes more negative. However, R remains constant. 
point moves on a circle with centre (0,0) and radiurs R in the complex
- plane. 
is positive and the point moves clockwise on the circle.
For movement away from the generator, the point moves anti-clockwise on the circle.
. Since VSWR
,
is constant for the circle. 
. This circle therefore is called the 
