the ideal receive antenna will be 1/2 the wavelength of the
radio signal, so:

AM .5 -1.6 MHz = 150 meters
FM 88-108 MHz = 1.5 meters
TV VHF 54-316 MHz = 2.3 - .5 meters

an antenna works best if it is "di-pole", two halves, each
side half the length above, the antenna wires(2) connect to
the middle. a meter is about 3 1/3 feet.

your TV antenna is good for FM because FM is sandwiched
between TV channels 2 and 13. a tv antenna is really a
series of antennas, an array of short, medium, and long
"rods" to cover the very wide range needed.

AM would require an antenna 250 FEET on each side, which is
not real practical. Most folks using an "outside" AM
antenna will settle on a wire 50-100 feet long to the
"antenna" connector, and as a substitute for the other
"half" will connect a good ground connection to the "ground"
connector. The ground used to be a water pipe, but since
it's now plastic, an 8 ft "ground" rod is driven into the
soil near where the "antenna" wire enters the house. At this
point it's a great idea to install a "lightning arrestor".
Lightning has a real affinity for "long wire" antennas, but
it's something you really don't want in your house!

AM and FM energies are not compatible on the same wire or
cable, that's why there are to sets of connectors.

Radio Shack has the wire, insulators, arrestor, and ground
rod to do this (or did a year or two back). You will find
there are AM radio stations on EVERY frequency on your dial,
in fact SEVERAL. Day, eve, night, late night, and early
morning you will hear different stations at the same spot on
the dial. For some folks, "logging" these stations is a
hobby. have fun, (it's good you don't have "short wave" on
your receiver ;-) google "short wave listener"

-larry / dallas




Mak Wilson wrote:
I have a relatively new hi fi stereo reciever. I also have regular
(properly grounded) TV Antenna (because I'm too cheap to afford cable).
The reciever has a hookup for an FM Antenna into which I run my
regular TV antenna and it works great for FM radio.

Now, I'd like to pick up AM stations. For some reason there is a
different hookup on the reciever for AM stations. Also, there is an
outgoing ground hookup on the back of the reciever which is supposed to
be just for AM Antenna ground.

I'm curious as to why there are separate antenna hookups for FM and AM,
but mostly I just want to know if I can safely and effectively use my
regular TV antenna for both FM and AM, ignoring the AM ground because I
know the antenna is already properly grounded.

Any help? Thanks.