[antennaware] Re: [TowerTalk] EZNEC files (a bit long)

[L. B. Cebik]

>
>I beleive that these are in binary format.  I don't have EZNEC, so am
>unable to look at the files.

EZNEC files are in a proprietary format, as are ELNEC files.  Any version
of EZNEC will read both ELNEC and EZNEC files, but ELNEC will not read
EZNEC files.

The advanced version of EZNEC (EZNEC Pro) can accept standard .NEC format
files, which are in ASCII, and there is a Save option to save an EZNEC
file in .NEC format.  In the latter case, all dimensions are converted
into meters, the basic .NEC measuring unit, although NEC has a unit
conversion card.

If one learns to read a .NEC file, one can enter the appropriate data into
EZNEC with only a little work.  A similar point applies to creating AO
files from EZNEC antenna model descriptions or creating EZNEC files from
AO models.  There is a note at my site showing the basic elements of a
.NEC file along with their basic meanings so that information re-entry in
an alternative system is possible.

The Nittany-Scientific site (www.nittany-scientific.com) has a fairly good
number of sample antennas relevant to amateur radio whose data can be
extracted and re-entered in AO or in EZNEC.  (Fairly good number = 35 or
so.)  My own site has among the notes a scattering of EZNEC model
descriptions that can be re-entered with fair ease.  Unfortunately, I do
not have an FTP directory to store the models used in the notes.  Another
pair of good sources of models that can be re-entered in other systems is
a. the collection of samples in AO and b. the collection of Yagis in the
YA program that comes with the ARRL Antenna Book--both of which
originate with K6STI and are worth study.  NEC4WIN from Orion also has a
fairly good number of sample antenna models.

Re-entry of antenna model data, including 5-6 element beams with tapered
element diameter schedules, can be speeded up by studying the model and
then using whatever copy feature a given program has--with subsequent
modifications to the element where it differs from the one copied.
Although having a complete model at hand may be convenient, it is far from
essential, since models can be rewritten into any system (within the
constraints of that system, of course).

Consider one more facet of the question of collecting models for any
particular modeling system.  If individuals contribute one or two models
apiece, they have no great vested interest in them, but the collection
process is necessarily slow.  If someone has a hundred or more models,
there will be a natural hesitency to dump them all for general use, since
the sum of time used either to convert them from another system or to
develop them from scratch will be high--and possibly deemed worthy of
recompense.  Hence, in the collection process, expect to go slow, but be
continuous in the effort:  decisions to contribute batches of models may
be made long after the initial inquiry/request, after the modeler has
thought a long time about whether they have more value as a sale item or
as a contribution to amateur education/service.  Although the modeling
programs we use have proprietary protections, I cannot say whether
models--which may represent original designs or the time/expertise
investment for conversion from other sources--have any such proprietary
dimensions.  However, if a modeler believes that there is such a
dimension, contributions may not be readily forthcoming.  Patience, then,
may be the key to developing a significantly large public access
collection.

-73-

LB, W4RNL



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