A radio perspective from my back yard
the map below for a very
large view of how the world looks from Winfield, British Columbia.
(Note: the map will open in its own window, so
you can read these notes while looking at the big picture).
radio beam heading map is centered on my home at grid square DO00hb.
map has an overlay showing two plots -- the visual horizon from
my back yard (old QTH in
red, new QTH
closer the line is to the center, the lower the mountains and the
more low-angle DX signals make it to the antenna.
concentric rings show the degrees of elevation to the highest terrain
in any direction. Remember, DX signals arrive at elevation angles
of 5 to 15 degrees. Domestic signals might be 25 to 80 degrees,
so terrain is less important there.
overlay plots show that my path to Europe is actually below the
theoretical horizon (anything inside that first ring) so I should
have good prospects when beaming Europe.
can see that my best directions cover most of Europe, the U.S. southwest,
and much of Asia. Any horizon line below about 5 degrees is pretty
can also see from the
red line that
my old QTH was FAR worse, as it was quite a bit closer to a very
high local mountain blocking the entire eastern horizon.
now live across the valley from the old place and the mountain is
still very visible from where we live now, but it is quite a bit
lower on the horizon and I can now look north and northeast for
many miles up the Okanagan Valley from Winfield to Vernon, BC.
Path Blockages and Open Spaces
another interesting analysis, I wanted an easier-to-comprehend visual
representation of just where I can expect to hear the most
low-angle signals. So I did an inversion of the Radio Mobile
data, and exaggerated it.
pattern is not on any real scale -- it's just a handy picture
showing the relative presence or lack of high terrain in any given
that the Canadian Maritimes are in the poorest area of the pattern.
Europe is in the best part, and much of Asia and the U.S. look good,
too. I haven't yet been able to compare the pattern to on-air experience
from this QTH, but I am looking forward to verifying it.
By the way, the home-made algorithm I used was:
Arbitrarily choose a maximum scale: 40
each terrain peak elevation and amplify it by 5 to exaggerate
that from 40 to arrive at an inverted number from the true Visual
- (Initial Terrain Elevation * 5) = Exaggerated, inverted data
Did I Make the Maps With Terrain Plots?
composite images were created from a variety of parts -- starting
with a bearing map centered on my latitude and longitude. I then
used a fabulous free program called Radio
Mobile by VE2DBE to explore my location's topography and tell
me what the radio signal horizon looks like.
took that data and used a charting program to create the plot and,
using a graphics program, superimposed the plot onto the original
beam heading chart and added a few helpful labels.
to do with the right software; harder to explain, hi.
Essential free program to find out where your station's best directions
are for working DX (and contesting). Tell the software your latitude
and longitude, and it will go on the Internet, download the topographic
data and display a color map of your area. The "Visual Horizon"
tool will graph the highest elevation in a circle around your QTH.
Circle Bearing Map Software
I used GCMwin to create the great circle bearing
maps for my QTH analysis. Great software, and it's free, too.