* You would equip each computer with a walkie-talkie.
* You would give each computer a way to set whether it wants to transmit or receive.
* You would give the computer a way to turn its binary 1s and 0s into two different beeps that the walkie-talkie could transmit and receive and convert back and forth between beeps and 1s/0s.
This would actually work. The only problem would be that the data rate would be very slow. A $5 walkie-talkie is designed to handle the human voice (and it's a pretty scratchy rendition at that), so you would not be able to send very much data this way. Maybe 1,000 bits per second.
Not mine....
look at how things work, they have a section on that. Wifi is pretty much the same thing as what you're talking about, just at much higher frequencies.