Walt,

As suggested, I looked up your paper in your website about "Additional
power lost in trans-lines due to SWR."

It is applied only to coaxial lines, of course, because the usual SWR
meter cannot be used on balanced twin lines. Actually it applies to
all lines.

I think your calculating formula is an approximation. It is due to the
SWR meter discarding all information about the PHASE ANGLE of
reflections. ie., the angle of the reflection coefficient (Gamma) from
which you have used to calculate SWR in your explanation.

Gamma has an angle which can lie in any of the four quadrants.
Theoretically this cannot be neglected.

I can't prove the approximation because I havn't the mental energy to
do the exact calculations involved.

For interest, my program SWRARGUE calculates the exact power lost in
the line for any SWR for a given input power of 100 watts. Power lost
is then a percentage of input power. Transmission efficiency then
follows. Note that the internal resistance of the transmitter or
conjugate matching is immaterial.

It does this by first of all calculating the input impedance of the
line, when terminated with the antenna feedpoint impedance, in the
form of Rin + jXin.

From the input power it then calculates the line input current and
volts.

From normal transmission line formulae it then calculates line output
current and volts.

It then calculates the power dissipated in the antenna input resistive
component. This is the power radiated.

The difference between radiated power and 100 watts line input must be
the power lost in the line. Line efficiency and the decibels follow.

The excess loss due to SWR is the difference between actual loss and
the line's overall matched attenuation, which is an input to the
program. Which, to me, appears to be an artificial way of looking at
things and your approximation arises from it.

The way to prove the point is to calculate the excess loss due to SWR
your way and compare with the results from my program.

I wouldn't be surprised if there's no significant difference. The
matter about the imaginary meanings of SWR and confusing reflected
power is not worth the trouble of arguing about.
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Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
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