CHAPTER 2 - Conveying Power at Radio Frequency
92
The same pattern repeats again
As in the case of Z
L
< Z
0
, when Z
L
> Z
0,
some of the power is reflected back to the source and
hence a standing wave is created along the line. It is apparent that the maxima and minima of the
standing wave are the same as the previous case. This is because the moduli of the reflection
coefficient are the same in both cases. Their signs however are opposite! This is reflected in the
phase difference between the standing waves observed for 25Ω and 100 Ω terminations and hence
different locations of maxima and minima along the line. An insight into the physical origin of such a
phase difference may be found in section 3.4.
You may also be interested to see 2D and 3D animations of the voltage along a transmission line for
selected load impedances. These may be found at
http://docfrankie.com/index_files/matlab_anim.htm
Another
useful applet is the Besser Reflectometer which may be found at
http://www.bessernet.com/Ereflecto/tutorialFrameset.htm
This applet allows to user to see what happens when a transmission line is terminated with any
arbitrary load.
t=T
Conquer Radio Frequency
92 www.cadence.com/go/awr
