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Re: [TowerTalk] Fwd: RE: NEC 5 upgrade

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Fwd: RE: NEC 5 upgrade
From: jimlux <jimlux@earthlink.net>
Date: Tue, 11 Aug 2020 06:52:53 -0700
List-post: <mailto:towertalk@contesting.com>
On 8/11/20 5:44 AM, Máximo EA1DDO_HK1H wrote:
Has anyone purchased NEC5 already?
Would be good to know if NEC5 engine works on 4NEC2.


73, Maximo
<http://foro.ea1ddo.es/>


Given Roy's statement about significant differences, I'll bet that NEC5 is not 4nec2 compatible. 4nec2 generates a NEC deck, runs the engine, and then parses the output file. If NEC5 uses a different format, or a different way of building the geometry, then it's going to be a tough conversion.

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


There is a comparison doc available, linked from the above.

"NEC–5 is essentially a complete rewrite of NEC. The input and output have been kept as much as possible the same as in earlier NEC codes. Some differences were unavoidable, since voltage sources in the mixed-potential method are at the ends of segments and on patch edges, while in NEC–4 they are at the segment centers. Patch input is di↵erent since patch edges must coincide to be connected..."

Of particular interest to most hams is that NEC4 is probably preferable to NEC5 for dipoles and Yagi antennas - see the last sentence.

"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."

________________________________
De: TowerTalk <towertalk-bounces@contesting.com> en nombre de john@kk9a.com 
<john@kk9a.com>
Enviado: martes, 11 de agosto de 2020 12:38
Para: towertalk@contesting.com <towertalk@contesting.com>
Asunto: Re: [TowerTalk] Fwd: RE: NEC 5 upgrade

So with no EZNEC Pro/5 in the foreseeable future, you would have
purchase the obsolete NEC 4.2 for $300 instead of the newer $110 NEC 5
version.  What other options are there for using latest and greatest
electromagnetic code license?

John KK9A





Dan Maguire AC6LA

Is there any word on W7EL upgrading to EZNEC Pro/5?


See https://eznec.com/nec-5.htm

Dan, AC6LA

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