..."There's an English NEC manual at http://www.nec2.org/. And, I'm
pretty sure that 4nec2 has an English NEC manual file included in the
distribution. The help file is certainly in English. It's fairly easy
to fool around with. "....
You are correct, Jim. I was thinking of the older versions when it
wasn't available.
-------------------
...." Hmmm. As I recall, mininec doesn't model ground or antennas
touching ground very well. NEC2 (or EZNEC) does ok, but not great,
especially with wires close to the ground. NEC4 (but you've got to pay
for that version). If you use the Sommerfield-Norton ground, you'll get
fairly good results with either NEC. These days, with fast computers,
there's no reason not to use it. 4nec2 takes care of running the SOMNEC
helper program multiple times for a frequency sweep. NEC4 doesn't need
it. "......
When you use EZNEC and select a MININEC ground it assumes no near field
ground loss, but it calculates far field ground loss for whatever ground
quality you select. So you have to manually insert a loss resistor to
simulate that near field ground loss. The value of that resistor you
can determine by looking in charts based on measured data. I think this
is much more accurate than constructing a radial field inches above a
Sommerfield-Norton ground, which is the only other option, since a
direct connection to a Sommerfield-Norton ground is not allowed. I
think both NEC2 and NEC4 underestimate near field ground loss. When I
compare calculated values with measured data they are always
optimistic. Whenever you place a wire very close to the ground,
measured data shows more loss than NEC2 or NEC4 calculate. Doing it the
other way, you can make the calculated data agree more closely with
measured data. This works OK for verticals. You still have the problem
with a very low horizontal dipole, but fortunately this isn't used too
often. The Sommerfield-Norton ground works OK if the antenna is not
very close to the ground.
Jerry, K4SAV
Jim Lux wrote:
> At 03:35 PM 2/12/2007, you wrote:
>
>> A full blown version of NEC2 including an optimizer. 4NEC2 (free)
>> http://home.ict.nl/%7Earivoors/Home.htm
>> Another site with reference info on the same program:
>> http://www.ok1rr.com/view.php?cisloclanku=2006022401
>> A disadvantage of this program is that there is no English version
>> manual, there is a German version. If you are just starting to learn
>> NEC then this one would not be the best choice because of that.
>
>
> There's an English NEC manual at http://www.nec2.org/. And, I'm
> pretty sure that 4nec2 has an English NEC manual file included in the
> distribution. The help file is certainly in English. It's fairly
> easy to fool around with.
>
>
>> I use EZNEC version 4 mostly. It does a few things that you can't do
>> with the other programs, although it does not have an optimizer like
>> 4NEC2. EZNEC has several ground choices and is easier to use for
>> vertical antennas because it allows the use of a Mininec ground,
>> although you have to manually insert the losses.
>
>
> Hmmm. As I recall, mininec doesn't model ground or antennas touching
> ground very well. NEC2 (or EZNEC) does ok, but not great, especially
> with wires close to the ground. NEC4 (but you've got to pay for that
> version). If you use the Sommerfield-Norton ground, you'll get fairly
> good results with either NEC. These days, with fast computers,
> there's no reason not to use it. 4nec2 takes care of running the
> SOMNEC helper program multiple times for a frequency sweep. NEC4
> doesn't need it.
>
>
>
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