> If the power reflects back and forth then that portion would never reach
the
> load would it?
Correct. In the case of a 50-ohm resistive source (e.g., a solid-state
transmitter without a pi-network, ATU, or other reactance network),
reflected power created by a line-to-load mis-match is absorbed by the
source (The PA in the transmitter), less a portion of the reflected power
absorbed by line losses.
> Doesn't a bird meter read higher forward power than there really is when
> there is reflected power.
Yes.
> So subtracting the amount of reflected power from the forward power
reading
> would not give you the amount of power reaching the load?
Someone keep me honest here with regard to the mechanics of a directional
coupler: Notwithstanding line losses, the amount of reflected power shown
by a Bird Thru-line Wattmeter is the amount of power reflected solely by the
line-to-load mismatch. The mismatch creates a 180-degree reversal of the
reflected *wave,* with respect to the forward wave at the juncture of the
line and load.
Whether the source is purely resistive, which absorbs all reflected power
(less power lost in the line), or if the source is reactive as in the case
of a pi-network or internal ATU, the Bird will still see the effect of the
reflection, in both forward and reflected readings, as a result of the
line-to-load mismatch. Except for line loss and assuring that the line
characteristic impedances matches the charcteristic impedance of the Bird
directional coupler, I do not believe any other portion of the system has
relevancy with respect to the indicated reflected power.
-Paul, W9AC
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