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![]() "Some Guy" wrote in message ... You guys are acting as if the engines and flight control surfaces of an aircraft are intimately tied to the plane's radio receiver, and the slightest odd or out-of-place signal that it receives is enough to send any plane into a tail spin. Not at all; however, there IS obviously a connection between various flight control functions (such as, say, the autopilot) and the information given by the avionics (esp. "nav" radios using ground-based sources such as VORs, etc.). It's not going to "send any plane into a tail spin", but it can certainly cause some problems. All this while the air travel industry is considering allowing passengers to use their own cell phones WHILE THE PLANES ARE IN FLIGHT by adding cell-phone relay stations to the planes and allowing any such calls to be completed via satellite. So I guess the feeble radiation by my FM radio (powered by 2 AAA batteries) is enough to cause a plane to dive into the ocean, but the guy next to me putting out 3 watts of near-microwave energy is totally safe. You DO realize that these are on very different frequencies, and that the emissions of an FM superheterodyne radio are very likely to fall right in the aviation band, don't you? Hint: if you have to go look up "superheterodyne" to understand this question, I have serious doubts regarding your qualifications to comment on it. Getting back to the original question (poor to non-existant AM reception), I understand the idea of aperature and long wavelenths of AM radio and the size of airplane windows - but what about the effect of ALL the windows on a plane? Don't they create a much larger effective apperature when you consider all of them? No. It's not the TOTAL area of the "apperatures" [sic] that is important, it's the size of the individual openings. If this were not so, then a conductive mesh could never be effective as a shield. And since the plane isin't grounded, isin't the exterior shell of a plane essentially transparent to all RF (ie it's just a re-radiator) because it's not at ground potential? No. "Ground potential" has absolutely nothing to do with it. Hint: what do you think is the RF environment within a perfectly conducting sealed enclosure, with respect to outside sources, even if that enclosure is completely isolated from any other surface or conductor? Bob M. (KC0EW) |
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