RichPowers

The following quote is from section 15.211 of the FCC OET63 bulletin ~Understanding The FCC Part 15 Regulations for Low Power, Non-Licensed Transmitters – http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf

Tunnel radio systems

Many tunnels have naturally surrounding earth and/or water that attenuates radio waves. Transmitters that are operated inside these tunnels are not subject to any radiation limits inside the tunnel. Instead, the signals they produce must meet the Part 15 general radiated emmission limits on the outside of the tunnel, including it’s openings. They also must comply with the conducted emission limits on the electric power lines outside of the tunnel.

Ok, I get it.. no I don’t.

Now, let’s just stop here for a minute… and just in case your thinking that I’m quoting this portion of the FCC bulletin as a means of leading up to some kind of wonderful loophole we could utilize somehow or something… I’m not. Nor is this an attempt at pointing out some important or usefull information.

No, It just struck me odd, and I’m curious why the FCC made it a point to specify such permision to lift the radiated limits for Part 15 in a tunnel to begin with?
 For what reason did they feel a need to bring this subject at all? Why??
 To me, it just seems weird.

But even weirder, and kind of funny to me, is what they say in the next paragraph..

Buildings and other structures that are not surrounded by earth or water (e.g oil storage tanks) are not tunnels. Transmitters that are operated inside such structures are subject to the same standards as transmitters operated in a open area.

Well thank you very much for letting me know, becuase I thought they were tunnels, and was just getting ready to start broadcasting inside of an empty oil storage tank till you told me that.

Is it just me??.. Why would they ever even say such a thing!
There has got to be some kind of story behind it all.

And I really wanted to transmit in that oil tank too.