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Mike Coslo wrote:
So is the lesson that Ladder line sucks, or is it that we shouldn't wash our ladder line with soap and water? 8^) Although I discovered it long ago, I keep getting surprised at how many people require a binary answer to any question -- is it good or bad, sucks or doesn't suck, good or evil. Sure makes it easy for our would-be politicians and their 15 second sound bite solutions to complex issues. Hopefully at least some readers will consider what Owen said, that the knowledge we've gained by this can hopefully help in the intelligent use of the line. Those needing a binary answer should look elsewhere; there are plenty of gurus who are more than happy to categorically state positive but simple answers to just about any question. I use a coin, myself, but each to his own. Wes' and my measurements, and Danny's observations, can't be directly applied to other situations. What they're meant to, and do, illustrate, is that significant loss *can* occur under some circumstances, and people who assume that twinlead or window line loss will always be low can be very much mistaken. Has anyone run tests on what "real" (open) ladder line does when you spray it with wetting agent and water? I don't think any result would be very meaningful, except to show, again, that significant loss could occur under some conditions (which I'm confident is the case). Those lines are often run with a very high SWR. The effect of conductivity and/or loss across the insulators would depend very heavily on the position and size of the standing waves. For example, if the SWR is high and the insulators happen to be at or near the voltage peaks, even a small amount of loss would have a major impact. But on a slightly different frequency, the antenna's impedance will change and the standing wave will move. If most insulators are near voltage minima, you wouldn't likely notice even quite a bit of loss. This effect would be most pronounced at higher frequencies where the spacing between insulators might become a sizable fraction of a wavelength, and not so pronounced at lower frequencies or with more insulators. But the magnitude of the SWR would still make a major difference. Roy Lewallen, W7EL |
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