I've read a lot about the K6MM vertical and may be forced to go that route, as
the Neighborhood Association has received some complaints on my current 160M
dipole and I may be forced to remove it.
Somehow, I feel that the K6MM design might be improved. I've been testing an
80M version using some military-style fiberglass mast poles with my helix made
out of copper foil tape. This has resulted in a much more tidy and easier way
to construct the helix. I also believe the 1.5 mil foil has less capacitive
losses between turns than the wire that is used by K6MM. I am using a
one-quarter inch wide foil tape on my 80M version, and with fairly close
spacing and a small capacitive hat, I can squeeze the antenna size down to only
8'.
I've been testing this antenna indoors in my attic, and it seems to work
remarkably well. I've gotten decent reports around the states, and have worked
some modest DX.
I have no idea how the foil tape helix could be modeled. I have built several
working helical segments using various diameter, tape size and pitch, and
measurements suggest that using a half-wave of foil tape in the helix will
yield a quarter-wave of electrical length. Every design I've tested seems to
show nice usable bandwidth against a fairly decent ground (center screen and 12
radials). I am wondering how the flat foil tape will perform compared to a
regular round conductor? Also, what width of foil tape would be adequate for
160M use? Has anyone modeled or experimented with this? Can the
My 80M version's performance gives me hope that a short 160M helical vertical
might work effectively as well. Any thoughts or suggestions will be
appreciated.
Thanks, Paul, K5AF
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|