Re: LF: Fenceline longwire

["Johan H. Bodin" <jh.bodin@telia.com>]

Rik Strobbe wrote:
> It seems that (at least in theory) even 1200 foot is too short to be 
> long  on 500kHz ...
> Or does MMANA not work properly ?
Hello Rik,

MMANA works very well for free space models but since it is based on MiniNEC, it 
does not properly model how the "real world" ground interacts with the near 
field. As far as I know, it uses the ground parameters for the far field 
calculations only. In other words, I don't think MMANA is able to make 
meaningful performance predictions for small antennas close to non-perfect ground.
I just put a 2000m horizontal wire into MMANA and tried different heights from 
1cm to 1m on 500kHz with real ground. Both gain and impedance figures were 
ridiculous, >600dB gain difference and sometimes the real part of the impedance 
was negative! :-D
Beverages rely on non-perfect ground to work so I saw no reason to trust the 
radiation patterns either.
73
Johan SM6LKM