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An antenna question--43 ft vertical
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July 9th 15, 08:42 PM posted to rec.radio.amateur.antenna
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An antenna question--43 ft vertical
John S wrote:
On 7/9/2015 12:40 PM,
wrote:
Jeff wrote:
On 08/07/2015 19:14,
wrote:
John S wrote:
On 7/7/2015 1:44 PM,
wrote:
Ian Jackson wrote:
In message , Jerry Stuckle
writes
Sure, there is ALWAYS VSWR. It may be 1:1, but it's always there.
If there's no reflection, there can be no standing wave. So, being
pedantic, there's no such thing as an SWR of 1:1!
Despite the name, VSWR is defined in terms of complex impedances
and wavelengths, not "waves" of any kind.
Actually, VSWR is defined as the ratio of Vmax/Vmin.
Actually, VSWR can be defined several ways, one of which is:
(1 + |r|)/(1 - |r|)
Where r is the reflection coefficient which can be defined a:
(Zl - Zo)/(Zl + Zo)
Where Zl is the complex load impedance and Zo is the complex source
impedance.
Note that a complex impedance has a frequency dependant part.
Note the the definition of VSWR uses the magnitude of the reflection
coefficient, |r|, which removes the phase and frequency dependant parts.
Jeff
The magnitude DEPENDS on the frequency dependant parts.
But the ratio of Vmax/Vmin does not.
So what?
P=E^2/R; does that mean current is irrelevant to power?
There is no one, true, written in stone, official and holy definition
of SWR.
All the definitions are equally valid.
--
Jim Pennino
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