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Old June 6th 05, 04:45 AM
Cecil Moore
 
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H. Adam Stevens, NQ5H wrote:

"Cecil Moore" wrote:
The log of the ratio of two SWRs doesn't seem to have much
meaning.


It's called db, Cecil.


The IEEE Dictionary says the ratio of power, voltage, and
current can be expressed in dB. It specifically states
that dB can only be related to power ratios or to parameters
that are proportional to the square root of power ratios.

SWR1 = [SQRT(Pfor1)+SQRT(Pref1)]/[SQRT(Pfor1)-SQRT(Pref1)]

SWR2 = [SQRT(Pfor2)+SQRT(Pref2)]/[SQRT(Pfor2)-SQRT(Pref2)]

The ratio of two SWRs will not reduce to a power ratio or
to the square root of a power ratio.
--
73, Cecil http://www.qsl.net/w5dxp

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