kk9k wrote:
>I want to try this antenna as my marginal cost will be zero. I have 4 33'
>verticals, an Ameritron RSC 8-V switch and plenty of radial wire and coax
>on hand.
>
>Any info on design and tuning will be appreciated. I believe the design
>has 3 "reflectors" that use the inductive reactance of the open feedline to
>make them "reflectors," right. How long should the feedlines be? I can
>tune with the MFJ 259B.
>
>Any models out there to tell me what to expect?
You didn't mention what you have for vertical support, and this may be
the dominant deciding factor. If it were me, however, I would look at
an array of 4 sloping dipoles on 40...switched at the center, and fed
in the center. If I recall the design the ARRL antenna book has, they
use 3/8 wave feedlines to a center switch. The result is one DE in
the desired direction, and 3 or 4 passive reflectors elsewhere.
I've seen both 4 and 5 dipole variants of this. The feedline shields
need to be isolated from the switch at RF, for optimal f/b & f/s.
The dipoles can slope straight, or the lower halves can fold back to
the base of the center support, in a kind of diamond. They don't require
a tower as a center radiator, so you can hoist 'em in a big tree.
This would be my 'small space' 80m choice. Possibly even 40, if I didn't
have clearance for a yagi.
N2EA
jimjarvis@ieee.org
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