You abviously didn't check well enough. The sensor is quite visible, and, although it is unknown what it is, it mimicks the appearence of old type IR remote controls for televisions/VCRs etc. I would assume that from the sensor, however, that the signals will almost certainly by light electromagnetic waves (invisible light), rather than radio electromagentic waves, which are what wireless networks and phone signals work on.
As for the other part, Nintendo has said that two sensors, to be placed at each side of the television set, are required to track the actions of the Revolution controller.
You might not need to have the device pointed at the sensors, but you will enevitably need to be in the same room so that any light signal can be detected.