On 12/9/2020 12:00 PM, wi6x.73@gmail.com wrote:
My gut tells me the 60.25197 + J 18.63926 ohms impedance is to high, but I don’t have
enough experience to know if what what I am doing is correct or not. I’m a neubie, at
EZNEC and 160m.
Those numbers tell you that the antenna is resonant below the band, and
the dimensions also show. It's a common trick to tune the antenna low so
that R is 50 ohms and X is inductive; we can then tune out the
inductance with series C. I'm using this technique with my Tee vertical
for 160M.
Feedline loss on 160M is pretty low unless the line is pretty long, so
if your rig or power amp will drive it, I wouldn't worry about it.
Another important observation. Four radials isn't enough of a
counterpoise unless they are well elevated -- N6BT, who's done lots with
verticals and is a fine antenna engineer, says at least 16 ft. A lot
of the R in your model could be ground loss. If those radials are
on-ground, you need a LOT more than four; they don't need to be any
specific length or even close to the same, but 100' is pretty close to a
quarter wave (thanks to soil modifying their VF), and more copper on the
ground is better.
Also, soil parameters strongly affect that loss component -- try to
learn what your soil is like, and plug those parameters into the model.
In the soil parameters window, right click on the entry screen to get a
list of them.
Here are slides for a talk I've done at Pacificon, Visalia, and to
several clubs. It's mostly about antennas and counterpoise/radial
systems. No original work, just summarizing a lot of great work by others.
http://k9yc.com/160MPacificon.pdf
73, Jim K9YC
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