That's called a "Coupled-Resonator" dipole. For details on modeling
something like that see:
https://ac6la.com/aecollection4.html#15b
Dan, AC6LA
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On Mon, 17 Feb 2020 14:41:19 -0500 Dave Sublette wrote:
I added a #14 THHN wire spaced 12" above my 40 meter rotary dipole. I cut
it to about 46 feet +/-. I modeled it on a program called Antenna Model.
With NO connection to the existing 40 meter dipole or its feedline, the
antenna is now a well matched antenna for both 30 and 40 meters. The
spacers were 1/2 inch fiberglass rods sawn from electric fence posts bought
at a local farm supply store. The stand offs were fastened to the dipole
element with short pieces of aluminum angle and U-bolts. I only used three
spacers for each half of the dipole.
This is the same technique pioneered by Force 12 antennas. It works.
73,Dave, K4TO
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