At the upper end of the spectrum ITU gives 3000 GHz or 3 THz as the upper limit of its jurisdiction. This is the region of infrared which is normally described by wave-length not the equivalent frequency, so for reference 3 THz is equivalent to 100 μm. While ITU gives a numeric limit for the upper limit of radio spectrum, there is some disagreement in the infrared/optics community of the lower limit of infrared technology with various sources giving numbers in the range of 1–3 THz.

For many purposes the difference between RF and infrared is the type of technology used and there is a growing convergence as many recognize that there is a transition zone where technology from both disciplines can be used together. Thus RF technology has be classically characterized by components such as mixers and antennas and infrared technology by lenses and diffraction gratings and new innovative systems use components from both traditions.

Tags: mmW