The 1 millimeter band is a portion of the EHF (microwave) radio spectrum internationally allocated to amateur radio and amateur satellite use. The amateur radio and amateur satellite band is between 241 GHz and 250 GHz. Amateurs operate on a primary basis between 248 GHz and 250 GHz and on a secondary basis in the rest of the band. Also, amateurs must protect the radio astronomy service from harmful interference between 241 GHz and 248 GHz. The ITU's allocations are the same in all three ITU Regions.