A radio perspective from my back yard

Click 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).

Interpretive Notes

This radio beam heading map is centered on my home at grid square DO00hb.

The map has an overlay showing two plots -- the visual horizon from my back yard (old QTH in red, new QTH in blue).

The closer the line is to the center, the lower the mountains and the more low-angle DX signals make it to the antenna.

The 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.

The 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.

You 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 good.

You 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.

We 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.

Relative Path Blockages and Open Spaces

For 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.

The 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 direction.

Notice 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
• Take each terrain peak elevation and amplify it by 5 to exaggerate the terrain
• Subtract that from 40 to arrive at an inverted number from the true Visual Horizon datapoints.

40 - (Initial Terrain Elevation * 5) = Exaggerated, inverted data

How Did I Make the Maps With Terrain Plots?

The 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.

I 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.

Simple to do with the right software; harder to explain, hi.

Radio Mobile software
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.

Great 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.