tremendously high frequency (THF)

Tremendously High Frequency (THF) refers to frequencies that are between 300 GHz and 3 THz. Their wavelengths are less than 1 mm and are referred to as sub-millimeter waves or micrometer waves.

ITU division of the entire frequency range between 3 Hz and 3 THz,

The THF frequency range also includes the terahertz frequencies, at least the frequency range up to 3 THz. The entire terahertz range is between 100 GHz and 10 THz. The THF frequencies are Dezi millimeter waves between 1 mm and 0.1 mm.

The THF range is above the Extremely High Frequencies( EHF). The ITU band number of the THF band is 12, which is directly related to the frequency range: 0.3 x 10exp(12) for the lower THF frequency.