Interestingly, when using *short* lengths of coax the loss can be lower
at high SWR than when it's matched. For example, 10ft of RG213 has a
matched loss at 1.9MHz of 0.03dB; but terminated with 500 Ohms
(SWR=10:1) the loss is only 0.012dB - less than half. For a 2500 Ohm
load (SWR=50:1) the loss is 0.046 - only 50% above the matched case.
It's only true for high impedance loads and short lengths, where only a
small portion of the standing wave pattern exists; but they could be the
conditions in this case.
Steve G3TXQ
On 09/11/2013 21:10, Carl Moreschi wrote:
How much coax did you add? The main idea of open wire line is it is
much less lossy than coax at high SWR's. You therefore want to keep
the coax portion is short as practical. The SWR on the feedline could
be 100 to 1 or even higher.
Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com
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