Hi Doug,
I have a 100-ft Rohn 25 tower that is series fed on 160 meters (there are
some VHF antennas on top that bring it close to resonance on 160, and a few
feet of linear loading at the base does the rest). This is over a field of
600 radials (arranged in a grid to accommodate parasitic reflectors and
directors that will be added soon.
I had the same idea to add 1/4 wave vertical wires hung off the tower. I
used no. 12 insulated wires cut to the formula 234/freq. mhz. I used some
scraps of PVC to space the wires out about 12-18 inches from the tower.
Each wire is fed directly with separate 75-ohm hardline. No additional
matching. SWR on 40 meters is low. On 80 meters it is high and I'm not sure
why and haven't taken the time to investigate -- but it radiates nicely
anyway (may need to work on the matching or use an isolation choke at the
feedpoint).
I put them up the day before the ARRL DX Phone contest -- I have a beam for
40 meters, but it is fixed on Europe so needed something for other
directions. And I had nothing up for 80 meters.
They worked quite well in the contest. I worked quite a few Pacific and
Asian stations. Since then I worked BQ9P too on 40m when he was barely
audible.
Once I get the 160 meter parasitics in place I plan to add parasitics to
the 80m and 40m verticals too so I will have 3 elements switchable in any
of four directions on each of the bands, all sharing the same radial field.
73/Jon AA1K
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