Frequency Spectrum & Allocations
By: Jean-Jacques DeLisle
[Register or Login at the bottom of this page to gain access to this download] From microwave ovens, heat we can feel, to the non-visible radiation of dancing cosmic bodies, electromagnetic radiation (EMR) is responsible for much of our technology and our perspective of the universe. EMR is photonic energy transfer with properties that vary along a continuous spectrum from infinitesimally close to zero cycles per second (Hz) to theoretically infinite cycles per second. With clever manipulation with electronic components EMR can be used to carry information we find useful through open air. This could be anything from high-definition video signals to emergency location transmissions.
As there are many competing uses for the frequencies of EMR that propagate through open air well, there are regulatory bodies that designate the portions of these usable frequencies, or the frequency spectrum. The regulatory agencies from across the globe choose ranges of the spectrum, or bands, and allocate which companies and which allocations can use that portion of the spectrum. To better explain the spectrum and to enable engineers to easily describe the frequency ranges they are working with, the spectrum is split into bands with common names. This process of naming was not standardized in practice for some time, and there are many naming conventions for frequency bands.
The “Frequency Spectrum” reference includes tables for the bands used by the International Telecommunications Union (ITU), The European Union (EU), North Atlantic Treaty Organization (NATO), United States Electronic Countermeasures (US ECM), and the Institute for Electrical and Electronics Engineers (IEEE). An additional table with the known and perceivable frequency spectrum is also provided for reference. To help generate a tangible connection with the sources of EMR, a scale is provided that depicts common sources of radiation. The relative sizes of objects that can be compared to the traveling wavelengths of EMR, is also shown. Curious to note, is that we can only see within a very small range of the known spectrum, and this is highlighted in the reference with a color bar.
For more information on the naming conventions of the spectrum, see reference, “Frequency Nomenclature.”