JB wrote:
If you use the (Z02-Z01)/(Z02+Z01) for the reflection coefficient, Fine!
But the line must be properly terminated resistively. Great for discussion
but real world gets complicated fast. As soon as the load gets reactive, the
phase between the voltage and current are different and the length of the
coax and it's velocity factor now contribute unless it is really short
compared with the wavelength.
You need to wade through the math. No matter what the phase,
the Bird directional wattmeter reads the forward or reflected
power referenced to its 50 ohm Thruline plus or minus 5%. If
that were not true, the Bird directional wattmeter would not
meet its published specifications. The phase is taken care of
when the sampled voltage and sampled current are added for
forward power or subtracted for reflected power.
Now tell me the truth, if the SWR is above 1.2:1, does that mean the radio
is making more power?
I certainly hope that is a rhetorical question. In a matched
system, the reflected power is part of the forward power. In
a matched system, the reflected power is redistributed back
toward the load and becomes a percentage of the forward power.
Source Power = Forward Power - Reflected Power = Load Power
If the SWR is not 1:1, the forward power must necessarily be
greater than the source power. Maybe the following web pages
will help:
http://www.mellesgriot.com/products/optics/oc_2_1.htm
"Clearly, if the wavelength of the incident light and the thickness of
the film are such that a phase difference exists between reflections of
p, then reflected wavefronts interfere destructively, and overall
reflected intensity is a minimum. If the two reflections are of equal
amplitude, then this amplitude (and hence intensity) minimum will be
zero." (Referring to 1/4 wavelength thin films.)
"In the absence of absorption or scatter, the principle of conservation
of energy indicates all 'lost' reflected intensity will appear as
enhanced intensity in the transmitted beam. The sum of the reflected and
transmitted beam intensities is always equal to the incident intensity.
This important fact has been confirmed experimentally."
http://micro.magnet.fsu.edu/primer/j...ons/index.html
"... when two waves of equal amplitude and wavelength that are
180-degrees ... out of phase with each other meet, they are not actually
annihilated, ... All of the photon energy present in these waves must
somehow be recovered or redistributed in a new direction, according to
the law of energy conservation ... Instead, upon meeting, the photons
are redistributed to regions that permit constructive interference, so
the effect should be considered as a redistribution of light waves and
photon energy rather than the spontaneous construction or destruction of
light."
--
73, Cecil
http://www.w5dxp.com
"According to the general theory of relativity,
space without ether is unthinkable." Albert Einstein