[TowerTalk] Verticals

[Bob Nielsen]

Of course, NEC4 isn't anywhere close to "free".

Does anyone remember using a stack of punch cards for NEC2 analysis?

On Dec 24, 2006, at 2:28 PM, Jim Lux wrote:

> At 09:49 AM 12/24/2006, D. Scott MacKenzie wrote:
>> I use MMANA quite a bit - it also has an implementation of NEC-2.   
>> It works
>> well, fast, and gets me in the ballpark.  I use it to see whether  
>> an idea
>> works, or to see what sort of changes I need to make.
>>
>> The best part of it - is that it is free.
>>
>> I would love to do a comparison between several different pieces  
>> of software
>> and see which one models the best, or gets accurate  
>> results....anyone have
>> any simple and more complicated models that they would like to  
>> compare?  It
>> might make a good article for QST or QEX.....
>
>
> There is already such a comparison. It's in one of the antenna  
> compendiums.
>
> Basically, all programs that do method of moments work about the same
> (many of them actually use the identical NEC engine underneath).  The
> differences are in convenience of user interface, and in some  
> "addons".
>
> NEC4 does produce better results than NEC2. It has better arithmetic
> codes, and, uses a slightly different way of representing the current
> distribution in each segment which has better numerical conditioning
> (i.e. roundoff doesn't bite quite so hard).
>
>   NEC4 also does much better at modeling wires close to ground.
>
> You definitely want to use the Sommerfield-Norton ground for either.