A QRZ member recently posted:
Solicitation for a computer antenna program
Due to discovering that my antenna model in the ARRL "crippleware version" of EZNEC has a 20~30% error I am looking for a computer software example of an inverted V. Either 4NEC2, MMANA GAL, or EZNEC models would be appreciated. For those who might like to help a old guy out, please send me a file for an inverted V by either PM or email.
FYI: emails asking for a copy of my current non-working EZNEC model will be ignored, I'm not interested in what I did wrong but how to do it right.
In reading another thread posted by the same member, it is apparent that he was trying to model a half wave inverted V dipole, though he clearly had the dimensions quite wrong, a lack of understanding of 2D geometry, much less 3D geometry.
The free version of EZNEC does have a limitation on the number of segments, but it has sufficient capacity to allow a quite good model of a half wave inverted V dipole.
The problems the poster had would be repeated in any comparable modelling
package because it was the model that was the problem, not the tools... you have
heard the saying
a poor workman always blames his tools.
Later he posted in a related posting
[u]nless I've made a mistake in my
calculations and previously built antennas 49' foot is the correct length for a
7 MHz dipole (24.5'+24.5'=49'). At least according to EZNEC. No, 49' is not
the correct length for a half wave dipole on 7MHz, not according to formula, not
according to EZNEC, and it is doubtful if the poster ever constructed such a
dipole (notwithstanding his assertion that he has). It turned out that one (and
only one) of the problems was that the OM apparently thought that the distance
between the ends of his Inverted V dipole was the same thing as the length of
the wire in the Inverted V dipole, a lack of basic understanding of 2D geometry.
This lack of high school trigonometry knowledge would be a handicap in using any
3D modelling package, not just EZNEC. The crippleware here in on the OM's
Having slagged EZNEC, and having been put on the right path by several posters who were prepared to engage this super ego, he has not at this time acknowledged that the problem was not EZNEC as he claimed, but simply, his lack of competency.
It is a credit to the patient helpers who, notwithstanding the poster's
warning that he was
not interested in what I did wrong (even via private
mail), that they have tried to help him.
This style of posting is more and more common on QRZ, and to a lesser extent on eHam. Posters, more often that not 'Extras' (as in this case), asking for information set out a whole list of pre-conditions to restrict responses. Of course, like this example, their lack of valid knowledge which prevented them finding the answer on their own, rules out responses that might solve their problem.
Some of us are humble enough to admit and learn from mistakes, mistakes are an important part of the learning process.
No links, no references, no names, it is an anonymous example... well as anonymous as the Internet is with Google out there!
VK1OD on the 'net. I appreciate feedback, click on the ... in webm...@vk1od.net for my email address.
© Copyright: Owen Duffy 1995, 2012. All rights reserved. Disclaimer.