"Dave Pitzer" wrote in message
...
First of all, I'm a novice where taransmitting antennas are concerned.

It seems to me that many AM "broadcast band" antennas are four-footed
towers. Do these towers merely serve to hold the actual antenna (a "wire")
off the ground vertically. The "wire" runs up the center of the tower?

FM and TV (and some AM) towers tend to be slim "guyed" towers with some
sort
of antenna element(s) at the top. Is this correct? Is the actual tower
ever
a radiating element?

The tower _IS_ the wire. Some towers have insulators at the base, some
don't, but the metal in the tower is what radiates. The guy wires might be a
part of the radiation system, but usually they're just anchors.

Also... Some tower structures (AM, FM & TV) tend to be cited on hight
ground -- mountains or atop high buildings. Other antenna structures tend
to
be intentionally located on "low" flat ground. Why the difference?

FM and TV signals use frequencies that travel best in a straight "line of
sight" from the transmitting to the receiving antenna; ergo, they're high up
so that more receiving antenna can "see" them. AM stations benefit from
being near water, and since the frequencies used for AM don't need to be in
a line of sight from transmitter to receiver, they can be low down where the
water is. If a station is using its AM tower to hold an FM antenna, the
location is a compromise between height (for FM) and proximity to water (for
AM).

Thanks,

Dave Pitzer

You're welcome. Please tell your teacher that r.r.a.a. sends its regards.
;-J

Bill