Julie and Anthony Bayerl of St. Paul, Minn., love watching prime-time shows on the sleek 50-inch television in their bedroom. They also love that they pay nothing for the programming.

The only thing they do not love is how a low-flying plane, heavy rain or just a little too much movement in the room can wipe out the picture.

“If someone is changing in there, it messes up your reception,” said Ms. Bayerl, a legislative assistant. “We try to stay very still when we watch television.”

The Bayerls are using an old technology that some people are giving a second chance. They pull free TV signals out of the air with the modern equivalent of the classic rabbit-ear antenna.