The Franklin is two vertical, co-linear half-waves fed in-phase. Google
will offer way more than you want to read. Obviously a large structural
challenge for a full-size one at MF. The one I built as a test was
heavily loaded and worked about like EZNEC-4 predicted. I think it's
insensitivity to "ground" may be one reason it works well, but that's
just a guess.
73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
Dan Presley wrote on 9/29/2022 12:20 PM:
Fred-can you share details on this antenna? Not familiar with it. Thanks.
Dan Presley 503-701-3871
danpresley@me. com
n7...@arrl.net
On Sep 29, 2022, at 12:08, Fred Jensen<k6dg...@gmail.com> wrote:
I've long wondered why hams haven't done more with Franklin verticals? KFBK
[1530 kHz in Sacramento] uses one located in the southern end of the Sacramento
Valley, and it's known as a Flame Thrower. I think KNBC [680 kHz?] in SF had
one back in the 50's sometime too. They're big at MF, but much more tractable
at HF, and they are amenable to loading techniques. I built one [fairly
heavily loaded] out of Buddipole parts I had, and its performance, particularly
when I was still activating summits, was surprising. Like a small loop, the
Franklin pretty much ignores ground ... although KFBK's probably likes being
located in rice fields filled with water. 😉
73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
Jim Brown wrote on 9/29/2022 11:28 AM:
David,
I've published a LOT of work on concepts like this.
This ran in National Contest Journal about six years ago. It's based on
extensive modeling, and was peer reviewed.
http://k9yc.com/AntennaPlanning.pdf
This was added to the ARRL Handbook or Antenna Book several years ago.
http://k9yc.com/VerticalDipole.pdf
This is an application of the above technique.
http://k9yc.com/80M-FDVertical.pdf
N6BT (original Force 12) has done a lot designs for monoband and multiband
verticals that are loaded dipoles. The multiband Cushcraft R-series and Hi-Gain
AV-series multiband verticals (companies bought out by MFJ many years ago) are
loaded dipoles.
73, Jim K9YC
On 9/29/2022 11:09 AM, David Gilbert wrote:
You're talking about a horizontal pair of AX1's ... I asked about them oriented
vertically. That wouldn't require them to be as high above ground as you
mention and would still allow them to be carried pedestrian mobile.
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