Gains with low wires (i,e. beverages) & MiniNEC based software are generally
(roughly) 6 dB in excess.
Honestly, I do not understand NVIS advantages, but this is another story.
73,
Mauri I4JMY
----- Original Message -----
From: "Pete Smith" <n4zr@contesting.com>
To: <antennaware@contesting.com>
Sent: Friday, June 07, 2002 1:17 PM
Subject: [Antennaware] Re: NVIS -- modeling, mininec vs nec-2 disparity
> At 09:51 PM 6/6/02 -0400, Guy Olinger, K2AV wrote:
> >Going to post this to antennaware, with the figures to see if the
> >gatheren already know about this.
> >
> >The antenna in question...two element reflector beam pointing straight
> >up.
> >
> >7.025 MHz, upper wire fed in center
> >
> >Upper wire = 67.5 feet long, 47.7 feet high (21 segs on eznec, 16
> >segs/hw mininec)
> >Lower wire = 68.4 feet long, 7.4 feet high
> >
> >AO (mininec) optimizes to these numbers, gets 11 dbi at 75 degrees
> >with 11.4 dbi straight up.
> >
> >Anyone know about this one and care to comment?
>
> I'm not sure how much of the context was on the reflector, so let me just
> add a little. The same model, with NEC-2 and Sommerfeld-Norton ground,
> shows a VERY different result. Instead of peak gain being at the zenith,
> it is at 41 degrees and maximum is only 5.99 dBi. With what EZNEC calls
> MiniNEC ground, results from NEC-2 are close to those Guy reports from
> AO. Since doubling the number of segments produces very little change in
> these results, I presume they represent good convergence.
>
> The question is, which modeling result is closer to reality?
>
>
> 73, Pete N4ZR
>
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