[TowerTalk] Fwd: RE: NEC 5 upgrade

[jimlux]

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 at contesting.com> en nombre de john at kk9a.com <john at kk9a.com>
> Enviado: martes, 11 de agosto de 2020 12:38
> Para: towertalk at contesting.com <towertalk at 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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