wrote in message . com...
(Maurizio) wrote in message . com...
Hi all,
Is there anybody with some experience in MF antenna modelling with
ground effect included (surface wave/space wave) etc. ?
I have the need to find out if the NEC4 is able to modellize this type
of antenna in a general environment and with which performance.
Otherwise, I will have to find out alternative ways (FEM/...).

I see you come from Italy, and (for as far as I know) the Nec4 core is
not (yet) available for none US citizens due to export restrictions.

You could consider using the Nec2 core. However not directly capable
of modelling burried radial wires you can simulate them by using
radial wires located some .001-.005 wl above ground (See www.cebik.com
for detailed info about this subject).

When modeling structures on MF (or LF) however you should also be
carefull not to violate segment length restrictions due to the
relatively low frequency compared to structure size.

You could take a look at the 4nec2 freeware
(www.qsl.net/wb6tpu/swindex.html) to see if the nec2 core is usefull.
4nec2 also has provisions for generating and visualizing far-field
patterns in which the surface wave is included.

Greetings,
Arie Voors.


Thanks a lot Arie for the links which as I have rapidly seen contain
many interesting references.
My experience is mainly in microwave (and up) frequency antennas, it
is the first time I look at these low frequency problems like ground
modelling and I see that this is the right newsgroup for this field.
If I will find some way to manage this problem better than how it is
currently done, I will keep you informed.
I would need to make a comparison between simulation results from MOM
and FEM programs of a common broadcast antenna to have a better view
of the situation.
Maybe that I can arrange such simulation comparison.

Thanks again