Antenna modeling, at least to determine maximal gain (phisical of the
array) is more accurate than any test environment.
A test environment is a useful tool when all the external parameters
are under control and/or some antenna "feature" is unknown (read trap
losses) and one knows how to read what's actually measured.
The basical limitation with modeling is the approximation of real
devices and the unavoidable simplification of the external evironment.
The test field limits, expecially when performed out of an anechoical
chamber, are the existing and uncontrollable parameters (ground wave,
side modes of propagation, reflections, etc.) or the impossibility to
warrant short and long term calibrations (instruments) or to measure a
resultant pattern (of direct wave and ground reflections).
Moreover, comparing HF lobes at angles (generally zero elevation) where
the lobe attenuation is already noticeable (to minimize reality) and
unwawnted modes or reflections are dominant, we may easily get false
results.
Using an accurate antenna modeling in a free space situation we can
know for sure what's the maximum gain obtainable by any antenna array
and we can compare antennas in a theoretical (but real) plain field.
Unfortunately that gain will be hardly obtained in practice and nothing
beyond real is actually true.
73,
Mauri I4JMY
> ---------- Initial message -----------
>
> From : owner-towertalk@contesting.com
> To : towertalk@contesting.com
> Cc :
> Date : Sun, 11 Feb 2001 22:51:35 EST
> Subject : Re: [TowerTalk] Dream on, he will have to prove it to
manufacturers on his de...
>
> In a message dated 2/11/2001 22:29:20 Eastern Standard Time,
W4EF@dellroy.com
> writes:
>
> >
> > BTW, are you planning to publish the range data with all the
details of
> your
> > scaled tests at
> > 2 meters (range description, reference antenna, gain, F/B, VSWR,
etc).
> That
> > would go a lot further
> > to proving your case than all the heated rhetoric that has been
floating
> > around here the last few
> > days.
> >
> > 73 de Mike, W4EF...............................
> >
>
> I agree on your point about the software, it is wonderfull tool, but
has to
> be used wisely and results checked out, especially in the "weird"
> configurations and close to ground. I am just in the process of
mastering
> EZNEC, trying to come up with arrays for the beach, so I can use them
in the
> upcoming contests. I will model Razors and see if they "work" on
paper too :-)
> The rest will depend on what I will decide to do with them. But the
more
> detailed Razor story will be coming up, most likely in one of the
magazines.
> Thanks you for your comments and support.
> I will have to shorten my lurking on reflectors, I keep typing
arguments,
> while work is not getting done.
>
> Yuri
>
> --
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