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Surfin’: I Can See For Miles

05/20/2011

By Stan Horzepa, WA1LOU
Contributing Editor

This week, Surfin’ considers elevation, weather and propagation.

I spent my first 32 years living in the city in the valley about 300 feet above sea level (ASL).

I’ve spent the past 15 years living in the country on top of one of the hills (about 1000 feet ASL) that surrounded the valley where I spent my first 32 years.

Do the addition -- that’s 47 years. I wish I was that young, but there also was 13 years between the first 32 and the past 15 that I spent in the country half way out of the valley or halfway up the hill.

Living on top of the hill versus living near the bottom of the valley makes for an amazing difference in VHF and UHF radio propagation. I can see clearly now line-of-sight-wise, instead of looking up at a wall of hills surrounding me, while trying to get  out of my RF hole by bouncing signals off 747s passing overhead!

It also makes for an amazing difference in the weather. The Missus often jokes about “our little house in the clouds,” but it is no joke. Living at 1000 feet ASL, the clouds are often so low during wet weather that they touch the ground here. (It may look like fog, but it is cloud.) When it gets thick out there and I can no longer see for miles, radio propagation goes the same way as my line of sight. Precipitation attenuates radio wave propagation.

Rain is worse than fog and causes “greater attenuation by scattering than by absorption at frequencies above 100 MHz.” Whereas, fog does not have much affect below 2 GHz. Snow falls somewhere in between (usually on my driveway).

Rocket scientists may find Radio Meteorology of interest (too much math in there for this space cadet). “Weather Versus Propagation” on Integrated Publishing's Electrical Engineering Training Series website is a better fit for me.

Until next time, stay dry, but keep on surfin’!

Editor’s note: Stan Horzepa, WA1LOU, looks out any window and sees clouds, or is that fog? To contact Stan, send e-mail or add comments to the WA1LOU blog.



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