THOUSANDS OF RADIO STATIONS FOR THOSE IN THE RIGHT PLACE 

To the average terrestrial listener the radio band sometimes seems restricted to provincial information. Quaint perhaps but ultimately boring. This appears especially true for FM whose listeners have increased dramatically during the past two decades. If you really want to hear thousands of stations, there is a way. Take your radio, FM, AM or short wave on your next plane flight. Reserve a window seat.

As soon as the plane levels out at high altitude, hook up the radio earphone, so you won't bother other passengers. Place the radio antennae as close to the window as possible. Switch first to the FM band. Then adjust the tuning dial. You will begin to hear dozens, then hundreds of stations. How does this happen? FM radio operates on line-of-sight transmission. On the ground at sea level, only nearby stations have a chance of transmitting their signal to your radio. These signals must penetrate or weave around buildings. As the distance from the antennae grows, the signal loses strength. In most urban areas 100 kilometres (62.5 miles) is about the limit. At higher elevations, you are able to bring in signals from a further distance. Radio stations try to elevate antennas to high buildings to widen coverage area. At 10,000 metres (35,000 feet) in an airliner, there is almost no limit to what you can receive. As you cross the continent, more stations come into range as you become closer to them, so their signals becomes stronger and block out the fading signals for radio stations you are flying away from.

The same applies to AM but to a lesser degree. You can certainly receive more AM stations from a high altitude but reception quality diminishes as you travel away from any particular AM station. After dark the "skywave bounce" phenomenon comes into play. AM radio waves are reflected off a layer of charged particles about 50 kilometres up in the atmosphere. The effect resembles an upside-down version of skimming a rock on the surface of a lake. The signals bounce long distances and provide reception unavailable during daylight. So many more AM signals become available under such conditions.

For real in-the-air excitement, try the shortwave band. First the relatively weak shortwave signals are coming through a minimum of lower level atmospheric pollution. Going up to your aircraft they may only be going through four to six kilometres of heavy atmosphere. After those signals clear 5,000 metres the much thinner air carries far fewer particles and the signals fly free. In such conditions the 10 or so kilometres up to your flying machine, for these signals, is easy compared to travelling thousands of kilometres along a sea level route (although over water is a better transmitting path than over land). Again, your radio receives more signals. During a recent 6,000 kilometre return-flight from Vancouver via Toronto and Miami to San Jose, Costa Rica (more than 20 hours roundtrip) to watch a solar eclipse for four minutes, I frequently listened to my Sony 2001 Multi-band radio. There are more than 10,000 radio stations in North America. I didn't hear all of them but I heard several hundred of them. You should too.

More information: Lawrence Magne, Editor-in-Chief, "Passport to World Band Radio" P.O. Box 300, Penn's Park, PA 18943. Cost, about US$20.

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