[600MRG] NEC4 cost

[Brian Pease]

What I like best about NEC4.2 aside from the slightly better results 
close to ground is the new availability of a current source to excite an 
antenna.
What I like least about NEC4.x is the difficulty in terminating 
(grounding) insulated wires buried in the earth.  It does very well with 
ground stakes that penetrate the surface.  I paid my license fee after 
having had a bootleg copy of NEC4D for many years.  As a registered 
Luddite, I still use direct punch card style data entry.

On 9/14/2015 8:06 PM, Rudy Severns wrote:
> W0RPK looked up the present costs for a NEC4 license, thanks Ralph:
>
>   
>
> "From https://ipo.llnl.gov/technologies/nec I learn that an academic and
> non-commercial NEC license is currently $300."
>
>
>
> If you want to model wires close to ground or buried you must use NEC4 for
> which there is a license fee.  I paid for my license some 20 years ago when
> it was much more expensive.  I had to forgo an upgrade to the station to pay
> for it but I've never regretted it.  NEC2 does quite well for elevated wires
> but cannot be used for buried wires and the accuracy degrades as you
> approach ground.  The freebee versions of NEC2 will do most of what we need
> for LF-MF.  It's more than adequate to evaluate and optimize irregular wire
> top-loading configurations and determine the lossless value for Rr, the
> radiation resistance, which you can multiply by the square of your antenna
> current to get your radiated power.
>
>   
>
> 4NEC2 comes with a NEC2 calculation engine.  However, it can also work with
> NEC4 if you have the license and the software you'll be given.  In the
> latest issue of the IEEE transactions on Antennas and Propagation there is a
> wonderful article on NVIS propagation.  That work used 4NEC2 with the NEC4.2
> engine and WSPR.  It's a fascinating bit of work by some Dutch engineers.
> It appears at least some of them were hams to boot.   The article suggests
> to me the use of a similar technique for LF-MF propagation investigations.
>
>   
>
> Over the years I've repeatedly compared modeling predictions to experimental
> results from antennas I've built.  I've been lucky to have good
> instrumentation which really helps.   When I was careful the results agreed
> very well, when I was sloppy, not so good.  There are several reasons why
> modeling and experiment may not agree: not observing all the modeling
> conventions, the model does not correlate closely with the actual antenna,
> poor instrumentation for the measurements and/or poor experimental
> technique.  Field measurements on antennas can be tricky.  I plead guilty to
> spending uncounted hours making absolutely worthless measurements with very
> expensive equipment.  I've had numerous opportunities to write articles for
> JOIR (the Journal Of Irreproducible Results)!  Few amateurs will have
> professional equipment and in the past the low end test gear available to
> hams has been pretty marginal.  But that's changing, we're beginning to see
> really good instruments (the AIM4170 for example) well under $1k and some
> now even below $500.  These days, I rarely use my fancy old HP boat anchors.
> The new instruments are so good and very convenient to use.  There are also
> many old instruments for sale on-line and at flea markets at reasonable
> cost.  One example I've been fooling with is a very elderly GR650 impedance
> bridge: black Bakelite panel, varnished wooden case.  These are usually
> given or thrown away!  The bridge originally operated at 1 kHz but it seems
> to work just fine when excited at 475 kHz.  Just the thing to measure your
> feedpoint impedance on 630m and 2200m.  Further testing and a write-up is a
> winter project!
>
>   
>
> The article on my web page I referred to earlier has a cutesy title stemming
> from a problem with a receiving antenna (a BOG) but the bulk of the article
> represents a serious attempt to check the validity of NEC4.2 modeling for
> wires close to ground or buried.  I needed to do this so I could
> convincingly explain the source of my problem.  In the Sept/Oct issue of NCJ
> Carl Luetzelschwab, K9LA, has an article on a BOG, he mentions replicating
> some of my modeling using NEC4.1 and got very similar results.  You don't
> have to have the very latest version although that's what you'll get if you
> buy a new license directly or the latest version of EZNEC Pro/4.
>
>   
>
> My suggestion is to start with the freebee 4NEC2.  I'll bet that once you
> get into modeling and having a lot of fun (it's addicting!), the license
> cost will not look so bad.  Christmas is coming!
>
>   
>
> 73, Rudy N6LF
>
>   
>
> _______________________________________________
> 600MRG mailing list
> 600MRG at w7ekb.com
> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>