[TowerTalk] MicroDEM

[Bill Tippett]

W3TX wrote:
 >Also, with regard to HFTA, any explanation why a station at the bottom of a
200ft hill that gradually rises the +200ft over 2 miles toward EU has a
better low angle coverage that the same antenna system on the top of a 50ft
hill that gradually falls -50ft over 2 miles toward EU?  This one doesn't
seem intuitive.

         You're correct that it does not make sense.  I would
double check your model.  In general, I would look for alocation with a 
gradual drop-off to areas of interest.  In
my experience (10 meters), the first half mile is the most
important.  This distance should increase as you go down in
frequency (e.g. first mile for 20m), but propagation stats
for lower bands are generally at higher angles than on 10m,
which somewhat offsets the need for the drop-off to extend
in a linear fashion for the lower bands.

         My terrain drops 85' in the first half mile toward
EU which seems to work well even though it rises back up
beyond that.

http://users.vnet.net/btippett/terrain_&_toa's.htm

This small 3-stack is competitive even with the top M/M's.

                                                 73,  Bill  W4ZV