[Antennas] Open Wire

2002年12月12日 15:21:43 EST

I
>> This thread on 450 ohm open line has been interesting. I use 450 ohm 
> ladder line
> here and it works great for me. This thread reminds me of my original 
> mentor when
> I got into ham radio some 55 years ago, who used 600 open wire feeders to a 
> random
> doublet. The late Wilson Rowell, ex W2HHL used a 135 foot doublet fed 
> with 600 Ohm
> open line at about 50 feet off the ground. The beauty of this antenna was 
> that in
> severe icing conditions Wilson would connect a 10V, 20amp filament 
> transformer across
> the 600 Ohm open line and melt ice off of his antenna. Remember that a 
> doublet is
> a closed circuit, so the antenna appears as a short to the transformer.
>> Some in North Carolina should have been using this in the past few weeks.
> I used a similar antenna at Eglin AFB back in 1966 when they first came out 
> with the
> first open wire feed line (before ladder line as we know it) and it worked 
> great,
> but of course there was no ice to worry about.
>> Bob Wilder, AF2HD/AFA2HD
>
Hi Bob,
The antenna you are talking about probably was a folded dipol,
a monoband antenna.
A doublet is never a closed circuit but consists of a dipol either coax fed
or driven by open wire for multiband use.
600 ohms open wire is much better then wireman 450 ohm ladderline.
This ladderline is very lossy compared to real open wire, maybe
OK for a fieldday (only for fun, not for win)
73
Peter
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