In AM Broadcasting, what is the polarization (vertical or horizontal)? What about FM Broadcasting?

Answer 1

AM broadcasting towers ARE the antennas. They are 1/4-wave ground-plane antennas. Sometimes there are more than one for phasing a particular pattern. The polarization on 1/4-wave antennas is always vertical, but by the time it gets to your radio there is enough scatter so that some radiation can be picked up in other planes.

FM broadcast antennas are much more complex. I've seen some slot antennas with decent gain, and circularly polarized planar fields (parallel with the ground). Other, cheaper ones have folded diploles that radiate horizontally omnidirectionally.

I worked at a 10-Watt public broadcast FM station once, they had a single folded diplole mounted high on a telephone pole that provided pretty decent coverage for a small city.

Mostly the polarization for broadcast FM is horizontal (but that leads to more ground loss).

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