Because DBS satellites are parked over the equator, DBS home dishes all point to the south. So if you had terrestrial transmitters pointing south, with receive dishes pointing north, you could use the same frequencies. In fact, you could use the same set-top boxes for both DBS and this terrestrial service, and merely add a second antenna and switch between the two antennas. That's the concept that Northpoint Technologies is pushing.
Trouble is, the idea is totally and fatally flawed, and nothing more than a grab for spectrum.
Northpoint, which is backed by several Republican Party bigwigs, has been gathering political support by pitching the idea that its wireless video service could be used to carry local television channels, complementing the DBS pay television service. Congress is under extreme pressure from constituents who face the cutoff of broadcast channels from their DBS service, because of copyright lawsuits brought by the TV networks. H owever, DBS operators don't want to partner with Northpoint. First, there are substantial interference issues. Second, Northpoint wants to use the whole 500 MHz of spectrum allocated to DBS, which is far more than is needed to carry a few local broadcast stations.