Don't forget that the vertical pipe if metal is part of the antenna
and/or the coax as well.
Simulation might show that you have to insert some common mode choke(s)
in the coax if using a non conducting pipe/tube to put your antenna on.
If metal is used you might have to adjust the length of the pipe for
best result on the band designed for.
This problem is mostly forgotten as the vertical pipe is mostly ignored
for the simulation, as is the cable.
73's
Aage-LA4ZH
On 13.07.2019 15:33, Guy Olinger K2AV wrote:
This thread is for Dave. So I'd rather not hijack this thread for a
separate and likely lengthy topic. So I will not comment here. Please start
a separate thread with a separate subject that includes "EZNEC
auto-segmentation". If you ever want yourself or others to be able to find
the discussion in the archives, a separate and pertinent subject will be
mandatory.
Thanks,
Guy K2AV, Antennaware Admin
On Fri, Jul 12, 2019 at 2:00 PM Mike Waters <mikewate@gmail.com> wrote:
Hello Guy,
It sound like you are saying that EZNEC's auto-seg feature should be
overridden in some cases. I am all ears, sir! :-)
The feature has *conservative* and *minimum recommended*, as you know.
Are there cases when even *conservative* is not good enough?
73, Mike
www.w0btu.com
On Fri, Jul 12, 2019, 8:17 AM Guy Olinger K2AV <k2av.guy@gmail.com> wrote:
Hi Dave,
What are you using for the vertical's counterpoise? What are you using for
the the ground type? Where is your source placed?
These are essential to answer your question.
73, Guy
On Fri, Jul 12, 2019 at 8:02 AM David Gould <dave@g3ueg.co.uk> wrote:
Most of my modelling has been with wire antennas but now I am modelling
some verticals with elements having diameters of between 38mm and 25mm
for 20m and 40m (and using drooping elevated radials made of wire)
I usually use around 9 or 11 segments for a 1/4 wave element. I noticed
that when I changed the number of segments the results for things like
feed impedance changed quite dramatically.
Are there some guidelines for the number of segments for a 1/4 wave
straight wire element?
How is the choice of segment length affected by the diameter of the
element tubing? Is there a limit on the ratio of segment length to
segment diameter?
73,
Dave G3UEG
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