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Post subject: Standing waves, doubts!
Posted: Thu Jun 09, 2011 2:08 am
Joined: Fri Jan 19, 2007
10:36 am Posts: 7
Hello, I have some doubts about standing waves on
antennas that hope you could clarify! As far
as I understood, in a transmission line where we
want only carry power from a source to a load, we
need to cancel the reflected wave by adapting the
load with the impedance of the line. The result
of this operation is S11=S22=0 and VWWR=1 that means
no standing waves. As far as I understood, in
an antenna we want to also avoid standing waves
by having VWWR=1 in order to avoid overloading problem
to the power stage. From theory I know that the
best radiating condition for an antenna is when
it resonates that is when there is a standing wave…
is that correct? How this condition is compatible
with a VWWR=1 for a good antenna matching? Is there
something that I’m not catching?
Post subject: Re: Standing waves, doubts!
Posted: Thu Jun 09, 2011 1:40 pm
Joined: Sun Aug 03, 2003
2:02 pm Posts: 451 Location: Erie, PA
A 1:1 VSWR (infinite return
loss) is definitely the preferred match condition
on the transmission line. The standing wave you
are thinking about is present on the antenna itself,
not on the transmission line, and even then, a perfect
standing wave is present only on a perfect antenna
at specific frequencies.