Sal M. Onella wrote:
"James Barrett" wrote in message
news:WN6dnT9x6ZU6I7HanZ2dnUVZ_v-

snip

I thought that I wanted
an antenna with zero reflected energy or as close to that as possible.
Now it sounds like that is not always the case.

You were mostly right; this is the theoretical ideal, but reality forces
compromises on all of us.

To put it simply, yes, you want the most power to "jump off the antenna"
into space. Whatever doesn't jump off is dissipated (wasted) as heat
somewhere in the system. If too much is reflected back from the antenna and
dissipated within in your transmitter, the transmitter overheats ($$$) or it
reduces power to protect itself and nobody hears you. . .

As I said earlier, there's a lot of misinformation floating around.

A high SWR doesn't mean there's "reflected energy" which is going to be
dissipated anywhere, least of all in your transmitter. Except for
transmission line loss (which admittedly will be greater, although
usually insignificantly so, if the SWR is very high -- see the Antenna
Book), all the power leaving the transmitter will arrive at your
antenna. Thinking of waves of energy bouncing back and forth looking for
somewhere to be dissipated will lead you down paths that you won't be
able to reason your way out of. As has been clearly demonstrated on this
newsgroup over and over. Read the Antenna Book and other good texts, and
don't try to make up additional imaginary waves.

"Sal" is right about one thing, though. Most transmitters will reduce
output power if the SWR gets too high, which tells the transmitter that
the impedance it's seeing is beyond the range for which it's designed.
(The problem is that various places in the transmitter can encounter
voltages and/or currents too far above design values, or impedances
which might cause instability. It's not because there are waves of
"reflected energy" which dissipate themselves in the transmitter.) So
you do want to keep the SWR measured at the transmitter below that
value. There's no harm in having a very high SWR on the feedline,
however, as long as it has low matched loss.

Roy Lewallen, W7EL