In message , Chuck
Forsberg WA7KGX N2469R writes
On Mon, 13 Dec 2004 08:47:43 -0600, Richard Harrison wrote:

Some Guy wrote:
"I have no trouble receiving FM radio broadcasts on a small am/fm radio
I sometimes listen to while onboard commercial jet sirliners (flying at
cruise altitude), but I bever seem to be able to pick up AM radio
stations. It`s just static across the AM band.

Any explanation for this?"

Fuselage of the airliner acts as a waveguide below cutoff frequency
(where diameter is at least 1/2-wavelength). Below cutoff, attenuation
soars rapidly.

FM wavelength is about 3 meters. AM wavelength is about 300 meters.
Propagation of FM inside the fuselage is OK. Propagation of AM inside
the fuselage vanishes quickly.

You need to stick the suction cups of your Zenith portable`s Wave Magnet
to a window to get AM reception.

Best regards, Richard Harrison, KB5WZI

Years ago I could get some shortwave reception by placing the
radio's whip antenna across the window and lowering the shade
to keep in place (and hide the radio). MW stations were generally
too weak to listen to. FM was a jumble at altitude.

These days RFI from the cabin entertainment systems completely
blanks out everything so don't bother trying. Be thankful MP3 players
still work.

With a window seat, FM works OK, especially (as has been said) with the
whip held close to the window. You can also get some SW reception. [I
remember listening to the BBC World service at 35,000 feet.] MW AM is
pretty useless (at those frequencies, the airframe is a Faraday cage).

Some airlines are/were OK about using radio receivers during the flight,
but I understand that these days, regardless of what the airline says,
you might get challenged by some 'over enthusiastic' security guy during
the normal departure security checks.

About 10 years ago (before the recent troubles), I did do some listening
on a UK-USA transatlantic flight. On approaching North America, I was
initially surprised that the first FM station I heard was
French-speaking (from Quebec, of course). I was relieved when I realised
that the 'driver' had not got lost.
--
Ian