CHAPTER 3 - Foundations of RF & Microwave Circuit Characterisation
124
Figure 3.1-2 Transmission Line Terminated with Z
L
, incident and reflected voltages
Now let us examine the expression for voltages and currents along the line
( )
The voltage is the sum of an incident part ( ) and a reflected part ( )
( )
( )
If we look at the expression for the current
( )
We can see that it is the sum of an incident current
( )
and a reflected current
( )
Note how both incident and reflected waves must respect the fundamental relationship which exists
between voltage and current at ANY point along the line, i.e. for any value of .
( )
( )
( )
( )
This is a very important point, DO NOT forget it!!
Z
IN
z=0
z =l
Z
L
Tx Line (Z
o
,g)
Z
L
l
V
L
I
L
(3.1-4)
(3.1-7)
(3.1-8)
(3.1-9)
(3.1-10)
(3.1-5)
(3.1-6)
Conquer Radio Frequency
124 www.cadence.com/go/awr
