> Several points --
> The most recent pubished source on this antenna is K3LR's article in
> the August 94 QST. Authors also include Jim Breakall, WA3FET, who
> knows a little about antennas. They switch both shield and center
> conductor and use a choke balun at the feedpoint. Since I don't know
> any better, that is what I did, too.
> The design has been in use by WA7LT, ex-W9LT for at least 25 years,
> and he told me personally that the antenna did not show directivity
> until he switched both.
> The feedline length from the switchbox to each feedpoint is somewhere
> in the vicinity of 150 degrees. In my modeling, that dimension is
> relatively non-critical, while the length of the dipoles themselves is
> quite important.
I understand the system better now Pete, thanks. But here is a
point to consider.
While that system probably works, with proper selection of feedline
lengths or use of baluns there would be no need to switch the
If you have to switch the shield, something was not planned as well
as it could have been. Shields should be cold, they should not have
common mode currents that affect patterns.
It is a big red flag when shields have to be switched, because that
means the shield is part of the radiating system.
73, Tom W8JI
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