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Re: [TowerTalk] NEC 5.0 ???

To: towertalk@contesting.com
Subject: Re: [TowerTalk] NEC 5.0 ???
From: "Lux, Jim" <jim@luxfamily.com>
Date: Thu, 11 Mar 2021 17:39:13 -0800
List-post: <mailto:towertalk@contesting.com>
On 3/11/21 5:03 PM, Artek Manuals wrote:
Chuck

The person I spoke to at LLL said the  $110 includes an Individual ( non commercial use) license , a copy of the "Windows Executable" and the manual to go with it

You can still get 4.2 if you want it $300 of an individual license, and a copy of the "source code". You then I guess have to write you own GUI and compile it or shell out $675 to W7EL net out of pocket $975

I ll probably spring for the $110 and hope the "windows executable" is useful to us mere mortals

Dave

NEC4.2 comes with windows executables and a variety of graphical interface programs (NECPlotG, PatplotPC), but as far as I can tell, no handy "geometry editor".


Of course, 4nec2 works really well with NEC4.2, and is free.   If they're licensing NEC5 for $110 for individuals, they might well license NEC4.2 for the same price. Or, they want you to fork out the $300 - they're really not in the "money making" business, but the hoops to set a price are numerous and many, and they probably don't want to fool with it.

It does come with complete source code, compilable for a variety of targets. I've compiled it for both Linux (Ubuntu, Debian, and RH) and for MacOS (Mojave and Catalina) using both gfortran and the Intel compilers.  It does assume you have the usual high performance libraries (LAPACK) which are freely downloadable. Getting it to compile isn't as simple as "make clean; make" but it's pretty close.


*Individual:*$110
*U.S. Academic:*$400
*Non-U.S. Academic:*$600
*U.S. Small Business:*$1,200
*Other U.S. Entity:*$1,700
*Other Non-U.S. Entity:*$2,400

https://ipo.llnl.gov/technologies/software/nec-v50-numerical-electromagnetic-code



https://ipo.llnl.gov/sites/default/files/2020-07/NEC5%20Validation%20Manual%20092419.pdf

describes the differences -> for *wire antennas and Yagis* NEC4 might actually be better.

"Many of the results here were chosen to illustrate known limitations of NEC–4, and NEC5 is seen to be more accurate for most situations. One case where NEC–4 beats NEC–5 is in convergence for a dipole, since NEC–5 uses linear, triangular basis functions while NEC–4 has a higher order sinusoidal basis. The mixed-potential code should converge faster with a higher-order basis, but there are no plans to add that to NEC–5. So NEC–4 may remain the preferable code for modeling antennas such as Yagis where accurate resonant frequencies are critical"

If you have small loops (Circumference<wavelength) near structures or wires connected to surfaces, NEC-4 does have problems. NEC5 or a specialized version of NEC-4 (NEC-4SL) don't have this problem.  (Jerry wrote this up in 1987, I don't know if the code is available or not)

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