> The real answer is that the reflected power is retransmitted on the next
> cycle and on and on every microsecond or whatever.
Assuming you are describing a situation where the transmitter and antenna
system are not matched, I wouldn't say that the reflected power is
"retransmitted" on the next cycle, but rather that the 1000 watts of
reflected power on each cycle is dissipated by the finals. Then, when
another 2500 watts of power is pumped into the system on the next cycle,
1500 watts get transmitted and 1000 watts get dissipated as heat in the
plates. In this case, you do have to subtract reflected from forward to get
the actual power absorbed by the load.
> Toms answer about subtracting the foreward from the reflected power to
> obtain the power absorbed by the load is accurate.
Yes, but it is only correct to subtract reflected from forward power if you
take the measurement at the transmitter output terminal. If you take the
measurement after the matching network (which could include part of the
feedline in some systems), subtracting reflected from forward power would
be incorrect, at least from the FCC's point of view.
In other words, if you use a tuner or matching network to obtain a match
between the amp and the feedline, the amp will not see the reflected power
(and hence the finals will not dissipate it). But a meter placed at the
antenna end of the feedline will show both forward and reflected power.
Both are absorbed by the antenna (and either radiated or dissipated as
heat.) However, in this case it would be incorrect to subtract reflected
from forward to get the output power.
Dick, WC1M
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