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