"Mike Painter" wrote

Well, sort of. I want to broadcast an FM radio
signal playing MP3 files in a variety of buildings
from single story homes to multistoried buildings.

From this, may one assume you envision having one
transmitter per building?

Small dwellings are no problems but the larger
ones present a problem. The location of the
broadcast unit may be mandated by factors beyond
my control.

The power needed to reach the opposite corner
might be to high.Is there any way to use
internal wiring as a short range antenna that
would be limited to the building for all
practical purposes.

This is practical for the AM broadcast band,
usually towards the low end around 550 kHz.
Search Google for "carrier current" radio
stations to get info on this technique.

Due to the relatively short wavelength of the
FM broadcast frequencies, a power line would
be too good an antenna and your signals would
be propagated beyond the confines of the
building. And they still might not reach where
you want them too. Still, it might work if
you could select the "right" power line to
excite.

The usual technique for limited-range VHF
(which is what FM broadcasting is) transmissions
is to install leaky transmission lines throughout
the desired coverage area. I have seen this
done to provide FM broadcast coverage inside
tunnels. In this scheme, a coaxial cable is
constructed with holes in its outer shield.
This couples a small amount of signal from
inside the cable to the outside surface of the
shield from where it is radiated into the
space immediately adjacent to the cable.

The obvious drawback of this scheme is the large
cable installation necessary for an extensive
coverage area.

Another possible solution that I can't find
an answer to would be to put the signal on
an unused TV channel if the building is wired
for cable.

Or combine a milliwatt-level FM transmitter output
into the other RF sources (TV channels) driving
the cable system. FM radios near the cable
outlets would pick up the signal from cable leakage.

I've done a lot of Google searching but can't
find anything specific.

Yeah, you need key words. Other than "carrier current",
or "leaky transmission lines", I can't come up
with any. I'll bet somebody else here can, though.

Jim, K7JEB