2.8 Reflection and Transmission in unterminated, shorted, matched and mismatched line
75
2.8.1 Open circuit termination
In this section we will show snapshots of what is happening in our transmission line at
different instants in time when the line terminated with an open circuit.
In each figure, the top graph shows the incident wave (in red), which travels to the right-
hand side of the page, and the reflected wave (in green) which travels in the opposite direction.
The bottom graph shows total voltage (in blue), which is the sum of incident and reflected waves,
along with its envelope (dashed magenta line).
Note that if we travel an integer number wavelengths, the signals at the two ends of the line have
the same phase!
We have picked two points on the transmitted and reflected waves (α and β) and we will
now see how they move along a line terminated with an open circuit.
At t=0s, the incident and reflected voltages are 180° out of phase hence their sum is zero!
It is apparent that when the signal finds an open circuit at the end of the line it gets reflected in its
entirety.
β
α
t=0s
Conquer Radio Frequency
75 www.cadence.com/go/awr
