The NATO I band is the range of radio frequencies from 8 GHz to 10 GHz in the system of letter designations for frequency bands used by NATO for electronic countermeasure (ECM) applications.[1][2] This is equivalent to wavelengths between 3.75 cm and 3 cm. It is a subset of the SHF band as defined by the ITU and corresponds to the lower half of the X band (8–12 GHz) as defined by the IEEE.[3][4]