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 Previous: The K7RA Solar Update |  Next: ARRL 500 kHz Experiment Kicking into High Gear |
By Stan Horzepa, WA1LOU
Contributing Editor
November 10, 2006
An affinity for airplanes leads to interesting anomalies in VHF /UHF radio propagation.
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I try and walk a mile or more during my lunch hour at work. As long as it is not precipitating, you will usually find me out there, no matter how hot or cold the temperature may be. Today, the temperature at noon was 69° F (21° C), an unbelievably warm November day for this part of the country. I shed my hoodie as soon as I stepped outside for my walk, and at about the halfway point, I shed my sweater, too.
I continued my breakneck 3 MPH pace, but stopped suddenly when I heard the sound of a jet airplane overhead. I looked up to find the plane and there it was almost directly overhead, an airliner with a red-orange body and gray-silver wings. I do this all the time, stop to see what is flying overhead. Most people I know (except for my sister) don't bother. I assume they are too busy to look up or too just don't care about what is flying up there.
Not me. I stop and look all the time. If I am indoors and hear something that sounds unusually low flying above the neighborhood, I have been known to run outside to see what it is. For all my troubles, I have not seen too much that is unusual. I guess the most unusual identified flying object (IFO) I have ever seen was a tanker refueling a bomber right over my house.
My sister and I always had this fascination with airplanes. I remember when we were kids; we would cajole Dad to drive us to the airport to watch the planes. Usually, it was a short trip to Tweed (HVN), Bradley (BDL) or the old Waterbury airport in Plymouth, but one time, we managed to convince him to drive us to Kennedy (JFK). What a great day that was!
My sister and I still "chase" planes, and are regular readers of "Ask the Pilot," a weekly online column written by pilot Patrick Smith, that I recommend to all airplane aficionados. Being a longtime computer hobbyist (that is a nice word for "nerd"), I have been also hooked on a variety of flight simulation programs over the years.
I never operated a ham radio from an airplane, although I once participated in an aeronautical DX operation with a fellow ham. My friend, Dave Genova, WA1TBP, had a friend, who had a plane. One weekend afternoon, he took TBP aloft and Dave had his trusty 220 MHz FM handheld with him.
The plan was to see how long we could copy Dave on 220 MHz as his buddy flew farther and farther away. They took off from a local airport and headed east towards Rhode Island and we finally lost TBP with Narragansett Bay in his sites. (And we haven't heard from him since!)
Before cable television, if I wasn't running outside to see what was flying by, I was inside watching the television signal flutter as a plane flew by. This flutter is known as the Mehrton Effect, that is, Aurora-like signal distortions caused by airplanes crossing the antenna beam. Volker Grassmann's Web site, DF5AI.NET, has a short piece about the Mehrton Effect, as well as other very interesting articles about VHF and UHF radio propagation with excellent graphics to boot.
I have mentioned Volker's site here before, but it is so good and ever evolving that it is worth mentioning again. If you have any interest in VHF/UHF, visit this site and it will expand your knowledge on the subject. Volker is also the author of BeamFinder, a fine "...software tool designed to conduct analyses for radio amateurs interested in radio propagation studies."
Until next time, keep on flyin' and/or surfin'.
Editor's note: Flying by the seat of his pants, Stan Horzepa, WA1LOU, writes Surfin' at least once a week. To contact Stan about airplanes, flight simulators, or anything else of interest, send e-mail or add comments to his blog.
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