Are directTV dishes energized in some way?
Yes, satellite dishes are frequently powered by DC current over the coax connection. The DC power comes from a "line power inserter" which will attach somewhere to the coax before it reaches the TV's. It may be a single connection or a splitter as well, but either design will connect to an outlet.



Edit: As others have mentioned in the comments below, the injector may also be built into your set top box.