It is broadcast on the same band as the communications, which is almost always in an unlicensed band (if your wifi network used a licensed band you would know -

It is broadcast on the same band as the communications, which is almost always in an unlicensed band (if your wifi network used a licensed band you would know -- you would have had to fill out a bunch of paperwork and pay a fee for your license). The point here is that anyone can monitor your wifi transmissions, not just the AP beacons, for any purpose.