> could see the bases of some of them were on a single point of an inverted pyramid
I was under the impression these towers were AM because such a long wavelength is needed for AM radio stations that the whole tower is the antenna, with an insulator between the point of the inverter pyramid and the ground.
FM towers are not like this; the wavelength is much shorter and the tower is not part of the antenna. The antenna is a short element at the top insulated from the tower.
FM antennas are indeed placed as high up as possible on these towers, but the tower itself, being a guyed model and not freestanding, does come down to a "ball and socket" joint at the bottom, which allows the tower to move around slightly under the tremendous pressure of the guy wires yanking it down to earth.
Apparently there's a deep 25'x25' slab of concrete underneath that holds the socket the tower rests on.
I was under the impression these towers were AM because such a long wavelength is needed for AM radio stations that the whole tower is the antenna, with an insulator between the point of the inverter pyramid and the ground.
FM towers are not like this; the wavelength is much shorter and the tower is not part of the antenna. The antenna is a short element at the top insulated from the tower.
Happy to be corrected.