In article ,
Texas Dawg wrote:

The other day I was surfing the web and saw an ad for a
cable modem, which won't do me any good because I don't
have cable, but, the thought crossed my mind, If someone
hooked up a cable modem to a TV antenna, pointed it at
their neighbors house where they had the same setup...
Would you be able to get a network connection between
those two houses?

No, for several reasons:

Cable modems expect very strong signals; far stronger than you could
ever collect with an antenna.

Cable modems are two-way devices, and will not function at all if the
"upstream" signal doesn't make it back to the headend. You'd probably
need a several-thousand-watt "booster" and a VERY LARGE antenna to send
that signal wirelessly to your neighbor.

All cable modems are "registered", and the provider knows where each and
every one is on the network, in terms of how long it takes the signals
to travel between the modem and the headend. No modem with a time delay
or a registration they didn't have on file would ever be allowed to
operate.

Isaac