A current project involves analysis of communications along trails during the Northern Virginia Horse Endurance Ride. Of the three annual events, this one, called “No Frills,” requires communication between two checkpoints and a base station.

Cell phones are of no use in the valleys. The VHF amateur radio bands are very good at knife edge diffraction propagation.

I use radio mobile along with elevation data to critique each link at three amateur radio bands: 6m, 2m and 70cm.

Links at 6m SSB

Links at 2m FM

Links at 70cm FM

Note, these links push the calculation algorithm beyond accurate measurements, but my experience shows these estimations hold up well enough to serve as a planning tool.

Examining the terrain between the base station and Gate & Go reveals the following three figures…

Terrain between Base and Gate & Go showing 50 MHz Link

Terrain between Base and Gate & Go showing 146 MHz Link

Terrain between Base and Gate & Go showing 440 MHz Link

Keep in mind the simulation software greatly exaggerates the terrain. The highest link angle to any peak is only 8 degrees. As shown UHF is of no use in such severe circumstances. Experience and simulation suggest 6m and 2m, with enough power, make the links from valley to valley.

In April amateur operators will test the effectiveness of the links.