Can you re-transmit an incoming cable TV signal wirelessly?

If you take the composite video output as well as the right and left channel audio, you can if you use a TV modulator. Problem is, they usually don't have much transmitting power and with a long antenna they just might make it to the next room. Any farther and you'd have to have either an amplifier stage on the modulator or a complete low power TV transmitter setup.

Just as a reminder, the FCC frowns on that type of thing, but if you keep it small 100 mw. or less, you could probably get away with it for awhile. The problem could be aggravated by what type of program you're repeating, especially if it's adult in nature and a neighbor's kid tunes in.