Definition of l band:
(N) :
the Institute of Electrical and Electronics Engineers designation for the range of frequencies in the radio spectrum from 1 to 2 gigahertz (GHz).
(N) :
The NATO L band is the obsolete designation given to the radio frequencies from 40 to 60 GHz (equivalent to wavelengths between 7.5 and 5 mm) during the cold war period.
(N) :
In infrared astronomy, the L band is an atmospheric transmission window centred on 3.5 micrometres (in the mid-infrared).