[TowerTalk] Loop vs Dipole...I'm original "asker"

Richards jruing at ameritech.net
Thu Jun 26 10:47:40 EDT 2008


With respect  (seriously) as a old student of Philosophy of Science
(Epistemology) I do not believe that Kelvin meant it quite as literal
you suggest -  but I like the quote and its application here.  Your use
of this bit, and your argument seems to be that the modeling program
is much more reliable for a given case than real life experimentation
in that case and that it is is not useful or practical or worthwhile to
actually test the antenna design, but just see what the modeling
program says.

So, I am sure there are others who would take a different academic
turn at t his juncture, and suggest the modeling is a close approximation
of reality, but one must, in the end, trust the empirical findings from
actual experimentation and real deployment of the antenna (i.e., take
actual measurements) to be sure it works as advertised in the modeling
program.    (Of course... we can get into quite valid debates over
whether or not we can trust the measuring equipment, methods, etc.)

But I do get your point and can see that you have a reasonable basis
for placing so much faith in the modeling software - especially as you or
the other guy was suggesting, it can save you lots of time, effort and
cost by modeling first before ever building anything, as I suppose the
modeling software could/might rule out a particular design from the
outset for some reason that is not immediately intuitively obvious.

Great stuff.   I appreciate you did not take my reply question as picking
a fight or being critical.  It is just that my own background makes me
somewhat more skeptical of the reliability of these programs, while
you have another take based on your background.

Happy trails and 743.  ========  K8JHR  ===========

=====================================================

Steve Hunt wrote:
> I'm with Jerry.
> 
> I reckon Lord Kelvin got it right in 1883 when he said:
> 
> "In physical science the first essential step in the direction of 
> learning any subject is to find principles of numerical reckoning and 
> practicable methods for measuring some quality connected with it. I 
> often say that when you can measure what you are speaking about, and 
> express it in numbers, you know something about it; but when you cannot 
> measure it, when you cannot express it in numbers, your knowledge is of 
> a meagre and unsatisfactory kind; it may be the beginning of knowledge, 
> but you have scarcely in your thoughts advanced to the state of 
> /Science/, whatever the matter may be."
> 
> So I place more trust  in my EZNEC results than in comments such as "I 
> tried this antenna and it worked really well".
> 
> I find EZNEC allows me to get an understanding of how an antenna "ticks" 
> that I couldn't easily get any other way. Of course its results wont be 
> reliable if the real world differs from the model, but I've been really 
> impressed with how well they hold up in the HexBeam work I've been 
> doing. Take a look at the "Real world vs EZNEC" plots on my website:
> 
> http://www.karinya.net/g3txq/hexbeam/eznec2/
> 
> As Jerry says - results that are good enough for Ham use.
> 
> Steve G3TXQ
> 
> K4SAV wrote:
>> NEC only provides an estimate of the results, but it is a very good 
>> estimate.  It is not 100% accurate, but it is good enough for ham use, 
>> and in many cases the accuracy exceeds the accuracy that you can measure 
>> by experiment.
>>
>> Jerry, K4SAV
>>   
> 
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