Run as much wire as you can conveniently feed in the middle. Anything
from 100 feet overall up to 326 feet overall (a double extended Zepp for
80 meters). 31 feet high is better for regional contacts on 80 meters
than 130 feet. (One year for FD at a wind energy site my radio club put
an 80 meter dipole up at 130 feet. It was too high for the local states
and didn't put a strong enough signal into the coasts to be a benefit.
With that center fed wire, use an open wire feeder (or TV twinlead, but
it won't last in the winter winds, its too aerodynamic) with a link
coupled balanced tuner (not something tuning through a balun) and you
can work 160 through 2 meters with that one wire.
The handiest and sturdiest supports are telephone poles or utility
poles. Next handiest are the multiple section telescoping masts, but
they need guying. I've use one attached to a 16' fence post, with the
guy wires going over stay wire arms and back to the base of the mast,
but they all eventually broke. I've used buildings and sections of Rohn
tower also. Tree's tend to cause some problems because of their motion
but if that can be accommodated by using a pulley and counterweight
(some use springs but not as successfully) they work.
The long center fed wire gets lobes at 45° to broadside on the next
higher band (e.g. 40m for one 326' long), then the lobes get closer to
the ends of the wires and more numerous as you go up in the bands. And
have a fair amount of gain. With deep nulls between the lobes, but as
those lobes are really cones, a little different arrival angle will fill
the null.
A trap or parallel dipole will also work but only for the bands its
made. The tuner plus open wire plus center fed wire will work most
anywhere that its more than about a quarter wave overall. I don't really
know its upper limit. I just used mine to work 300 mile paths on 2m CW
and SSB for several years and hundreds of 6m contacts during VHF
contests.
73, Jerry, K0CQ
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