Sierra Leone fluorescent tube antenna
You realize, of course, that it's the horizontal wires running along the tube that functions as the antenna &mdash; the fluorescent tube itself contributes nothing to the process, other than providing a "standard length" for the assembly.

As for the article that Tony found, it's a bit like catching birds by putting salt on their tails. If you have to run a coax cable to every fixture anyway, you might as well install an ordinary cheap WiFi antenna, which will work regardless of whether the light is on or off.