On Fri, 26 Jun 2009 12:52:04 +0300, Vytenis Sciucka wrote:
You have gotten excellent advice from others, especially Pete and Bill,
but I will add this about the terrain data. I've used HFTA a lot, and so
have many hams who live near me. We find it to be a very good predictor of
the propagation of horizontal antennas. To use it, you must enter terrain
data for your location. In the US it is easy to get this data, because it
is published by our government on the internet. It is also possible to
obtain the data from paper topological maps (that is, maps that show
elevation of your terrain). To do that, you first find the map, then mark
your QTH and draw radials from your QTH to the directions you want to
study. Then mark points at regular intervals on each radial, note their
elevation, and enter each point into HFTA. I've done this for two radials
from my QTH, before I found the data on the internet. It takes more time,
but it works.
N6BV is my neighbor, and a member of our Northern California Contest Club.
He often gives us advice on many things, including HFTA. I live on the
side of a mountain, so the radials go up and down a lot. He advised me to
carry the radials out to about 5 miles (8 km). If your terrain is flat,
you don't need to enter terrain data, but if it goes up and down, it is
VERY important that you enter it to get accurate answers.
Jim Brown K9YC
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