I put the base even a little further away than that so lower antennas can
rotate and there is less coupling. From my modeling the tower can skew the
pattern even 100+ feet away. Antenna placement is a compromise for most of
us.
John KK9A
Edward Sawyer N1UR
My thoughts would be the following on this:
Bringing the feed point about 20 - 25 ft away from the tower and letting it
slope up to the high point would help to de-couple. Obviously the radial
system would have to be adjusted.
At 4 ft, some coupling to the tower is occurring and if you assume that as
the case, you should actually tie the base of the tower to the radial system
so that at least the coupled full system efficiency is improved (this is the
easiest first step since it doesn't move the radials). A re=matching of the
feed point impedance will likely be required when doing either of these
steps.
73
Ed N1UR
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