The article by Wes Stewart that I referenced earlier:
was published in the ARRL Antenna Compendium Volume 6. It shows measured
losses for various commercial ladderlines when wet and dry. For example,
the loss of Wireman 551 increased from 0.33dB/100ft @ 50MHz to
5.8dB/100ft @ 50MHz; by contrast the loss of a home-made open-wire line
comprising #16 wire spaced 0.75" was 0.3dB and did not change when wet.
By the way, ARRL figures in the Antenna Book, and in their TLW software,
for ladderline grossly under-estimate the loss. If you do the basic RF
resistance calculations you'll get losses almost exactly double the
values they quote; I can't help think that whoever did those
calculations might have forgotten there are two wires :)
On 26/01/2012 18:20, Jim Brown wrote:
> On 1/25/2012 10:54 PM, Rick - DJ0IP / NJ0IP wrote:
>> He found when the window-line gets wet from rain or snow, its impedance
>> changes a little and you have to re-tune your matchbox - but the efficiency
>> is still the same.
> In one of the excellent ARRL Antenna Compendiums, Frank Witt published
> the result of his research (including careful measurements) of loss in
> open wire line and window line when it gets wet. Frank is a real
> engineer. W1ZR is not -- he is a writer, and his writing in QST is full
> of technical errors.
> 73, Jim K9YC
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