At least four television stations have petitioned the FCC to reassign their digital broadcasts from a VHF channel (2 through 13) to a UHF channel (14 through 51). (Note that UHF channels used to go up to channel 83, but the frequencies for channels 52 to 83 were auctioned off as part of the transition to digital broadcasts.)
There are many reasons for stations to want to switch. VHF stations are typically limited to lower transmission power, and the error-correction technology in the ATSC signal works better at the UHF frequencies than in the VHF range. And UHF transmissions work better in the “concrete canyons” of a major city.
And then there’s the antenna problem; many vendors sold “digital TV antennas” to an uninformed public, which were simply high-performance UHF antennas that cannot receive VHF signals well. As a result, many households that were “prepared” for the transition to digital broadcasts cannot receive VHF channels. Many broadcasters temporarily transmitted their digital signals in the UHF range, so all appeared to be fine before the transition. But they switched back to their “normal” VHF channel after they stopped their analog broadcasts. As a result, these stations have lost hundreds of thousands of viewers.
The stations that have either made the switch or have requested permission are WHDH in Boston, WLS in Chicago, KKTV in Colorado Springs, and WWAZ in Fond du Lac, Wisconsin.
Note that these changes refer to the actual frequencies that are used for the transmissions, and may have nothing to do with the assigned “virtual” channel that shows up on your TV tuner. If you live in one of these markets, you will need to set your digital tuner to rescan after the station makes the switch. Its virtual channel will remain the same, but the tuner will identify its correct transmission frequency when it performs the scan.