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Old December 13th 04, 07:52 PM
Bob Myers
 
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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)