Sure it does!
The losses in feedline at HF are overwhelming due to I^2R copper losses.
If you look at the current distribution along a matched line it's flat;
for example, flowing 50W into a matched 50 Ohm load the current will be
a steady 1A along the line. Now look at the current distribution when
the line is terminated in 500 Ohms (SWR=10:1); there's a current minimum
of 0.316A at the load and the current increases as you move back along
the line from the load. Far enough back from the load the current will
peak at 3.16A, but for electrically short lengths of line the RMS
average of the current distribution will be well below 1A and so the
losses will be lower than in the matched case.
Try it in VK1OD's calculator; but don't try it in a calculator that only
accepts SWR rather than load impedance - they can't possible give you an
accurate answer under these conditions.
Steve G3TXQ
On 09/11/2013 22:14, Carl Moreschi wrote:
That's a new one on me. How could loss be less with high SWR on a
short length of coax? It makes no sense.
Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com
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