Dan Levin wrote:
> I'm planning to install a vertical for 160, and want the bandwidth to be as
> wide as possible.
>
> The easiest way to make bandwidth go up is to make conductor "thickness" go
> up - i.e. to use bigger wire (in this case, the radiator is wire).
>
> I recall from something that I read ( likely on L.B.'s website, RIP L.B. ),
> that one can make a wire electrically thicker by paralleling two wires some
> distance apart (say 6 - 12", think of them as the tracks of the train track)
> and connecting them together every so often with a horizontal wire between
> them (the ties). Like ladder line, but with short wires connecting the two
> sides every so often.
>
There used to be some dipoles made like this in the old handbook. I
don't know if they are still in the current "Handbook", or Antenna
Handbook. They do substantially increase the bandwidth when used in a
cage fashion on 75 and 40. This also results in the antenna being a bit
shorter. I've never used one specifically like this, but I have used
"fan dipoles" constructed of several wires with the ends separated by
3 to 6 feet. With a dual band 75 and 40 I've also used a "fan" with the
ends about 8 to 10 feet apart and they pretty much acted like separate
dipoles although the extra capacity resulted in them being a bit shorter.
If you have the room to hang a quarter wave wire on 160, I'd go the cage
route, but I'd make the cage a good 3 to 6 feet across with 6 to 12
wires. The problem with a large and long cage is the need for spacers in
addition to the ones at the top and bottom, or a lot of tension. That
means the support is going to need to be quite strong.
To make the bandwidth go up much on 160 will take a sizable cage.
Remember that even a doubling of the bandwidth of a 160 meter wire
antenna is only going to give maybe 60 KHz. It's been a while since I
used the 160 antenna here so I don't remember the exact BW but it is
*narrow*. However with a tuner in the line I can operate the whole 160
band. OTOH I need to keep the antenna resonant some where between the
middle and top end of the band. With it resonant at the bottom end, the
tuner will arc when operating near the top end of the band at the legal
limit.
Good Luck,
Roger (K8RI)
> Does anyone have any practical experience with such a beast, or a pointer to
> a reference for me?
>
> In particular, I'm planning on two wires 12" apart (to make a virtual 12"
> conductor), and am wondering how far apart the connecting wires can be (the
> short ones).
>
> Thanks!
>
> ***dan, K6IF
>
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