Hi Jim,
There are many ways to skin that cat. It's pretty well known that radial
systems don't need to be anywhere near ideal to work. The radial system
for my Tee vertical covers about 220 degrees. In 19 years, I have 173
confirmed on topband.
These are slides for a talk I've done at Visalia, Pecificon, and to
several clubs. Mostly it talks about radial systems and other
counterpoises.
http://k9yc.com/160MPacificon.pdf
Also, losses due to SWR, (SWR is determined by the match between the
antenna at the feedline) are pretty low at 160M, especially for
decent-sized coax, even for fairly long lines. What matters is then
matching the transformed impedance to the power amp.
Freeware called SimSmith is quite good for designing matching networks
for measured complex impedance sweeps of the antenna in the shack. EZNEC
is quite good at designing antennas if given all the relevant data,
including significant surrounding objects and a first approximation of
soil characteristics. Rudy Severns, N6LF, has done a lot of extensive
and spectacularly good work on radial systems. Settle into a comfortable
chair with coffee or a nice scotch.
https://www.antennasbyn6lf.com/
https://www.antennasbyn6lf.com/design_of_radial_ground_systems/
73, Jim K9YC
On 5/6/2025 9:15 AM, jim.thom jim.thom@telus.net wrote:
Has anybody used a 1/4 wave sloper (for 160m, aprx 120-130') hanging from
the top of a 89' crank up tower before ?
Due to the 5 x sections overlapping, the feed point would have to be at the
very top of the tower. IE: it can't be part way down from the top.
Will it work with some top loading, like a 3 el 40m yagi ? Right now, my
modified F12 340N yagi has all 3 x els insulated from the boom. ( oem LL
wire loading replaced with hb 3/8" tubing coils). I was seriously
thinking of bonding the REF and DIR to the boom, to increase the top
loading. REF is aprx 59' long. DIR is aprx 52' long.
I can't shunt feed the tower, since grnd mounted radials are out of the
question. House is blocking the path of any radials > 180 degs.
Jim VE7RF
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