At 03:44 PM 12/8/2005, AD5VJ Bob wrote:
>Does anyone know all the factors that affect the angle of
>radiation from a horizontal dipole.
>
>Height being one of course, but are there others that
>raise or lower the angle and /or broaden or narrow the
>pattern.
>
>Has anyone ever really done a study on this?
Not to be glib, but the answer is yes, hundreds and hundreds of people have
studied this. Such studies, from both a theoretical and experimental
standpoint, form the basis for such useful programs as NEC.
Now that computers are fast enough, it's really interesting to put a simple
horizontal dipole model into a decent code that renders the pattern, and
try changing things, like the lengths of the wires, the position of the
feedline, whether it droops, putting in other things near it. Modeling a
dipole over real ground takes a few seconds on a moderately fast Pentium A
couple or three hours of fooling around can be quite interesting.
I just ran a single dipole using NEC4 (using the 4NEC2 front end) over
Sommerfield Norton ground, and it took 2 seconds all told to run the model
and display the 3D pattern on a 3.6 GHz Pentium.
A modeling program makes it easy to systematically change something to get
a good intuitive feel for what will happen. As you move the dipole up, you
can see the lobes changing. Actually, now that it comes up, I wonder how
hard it would be to render an animation of something like this.
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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