|To:||"Jim Lux" <email@example.com>,"Towertalk" <firstname.lastname@example.org>|
|Subject:||Re: [TowerTalk] Modelling a basic stack|
|From:||Pete Smith <email@example.com>|
|Date:||Mon, 10 May 2004 13:51:36 -0400|
At 09:17 AM 5/10/2004, Jim Lux wrote:
The desktop computer might be powerful enough (especially if you're willing to wait overnight), but I think you're also looking for a modeling program/system that is reasonably inexpensive and doesn't take hundreds of hours to use effectively.
Thanks for the info. Yes, I was thinking in terms of something that "we" (amateurs) could both afford and put to reasonable use.
I had heard of NEC-BSC, but had the impression that it was principally used for problems like antennas placed in the superstructure of ships, rather than above real ground. A quick Googling found only that sort of application.
Jim speculates about the effects of earth properties on the modeling fidelity. I tend to rely on Dave Leeson on this. If I understand what he writes on page 10-2ff of "Physical Design of Yagi Antennas," this is relatively unimportant. He writes, "The reflection is from the conductive or dielectric discontinuity between the air and the surface of the ground (giving effect to skin depth), not from some magical underground water layer."
Jim also comments (in part of his message I did not quote) on the potential usefulness of data from Landsat Thematic Mapper. HFTA's 2-D terrain profiles are generated from USGS's seamless data server. Its 1 and 3-meter resolution data are derived from Thematic Mapper and Shuttle radar mission data, if I understand correctly. In any case, a whale of a lot better than drawing pencil lines on a topo map.
73, Pete N4ZR
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