On 9/1/2010 11:54 AM, Ian Jackson wrote:
The SWR on a feeder will always be greatest at the load end. However,
because of the feeder losses, the power will also be lowest at the load
end.

So, although the power loss per unit length (in dB) due to SWR will
steadily increase as you approach the load end, because of the feeder
loss, there will be less absolute power (in watts) to lose as you
approach the load end.

The question is, at which end of the feeder is the most absolute power
lost per unit length?

At the transmitter end. Suppose you have a 100 watt transmitter and a
cable with 3 dB loss per 100 feet.

50 watts is lost in the first 100 feet
25 watts is lost in the next 100 feet
12.5 watts is lost in the next 100 feet

and so forth. If you were to divide this up more finely and plot it,
you'd find an exponential decay of watts loss per unit length versus
distance from the transmitter.

Roy Lewallen, W7EL