Radio Frequency Bands

The certified spectral range of our sub-terahertz imaging cameras (50 GHz – 0.7 THz) borders with other portions of electromagnetic spectrum, and therefore it makes sense for us to describe briefly the adjacent spans and their peculiarities.

The radio spectrum (also known as radio frequency or RF) is one of such parts of the electromagnetic spectrum that overlaps our sub-THz range at its lower end. Accordingly, Electromagnetic waves in this frequency range are called radio frequency bands or simply ‘radio waves’. RF bands spread in the range between 30 kHz and 300 GHz (alternative point of view offers coverage 3 KHz – 300 GHz). All known transmission systems are operated in the RF spectrum range including analogue radio, aircraft navigation, marine radio, amateur radio, TV broadcasting, mobile networks and satellite systems.

RF frequency bands

To prevent interference between different users, the generation and transmission of radio frequency bands is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU). The ITU (based in Geneva, Switzerland) is a member of UN development group, coordinates the shared global use of the radio spectrum, promotes international cooperation in assigning satellite orbits, works to improve telecommunication infrastructure in the developing world, and assists in the development and coordination of worldwide technical standards.

Different parts of the radio spectrum (RF bands) are allocated by the ITU for different radio transmission technologies and applications; some 40 radio communication services are defined in the ITU’s Radio Regulations (RR).

A radio frequency band is a small contiguous section of the radio spectrum frequencies, in which channels are usually used or set aside for use. For example, broadcasting, mobile radio, or navigation devices, will be allocated in non-overlapping ranges of frequencies. For each of these bands the ITU has a band plan which dictates how it is to be used and shared, to avoid interference and to set protocol for the compatibility of transmitters and receivers.

Pursuant to convention, the ITU divides the radio spectrum into 12 bands (as shown in the table below), each beginning at a wavelength which is a power of ten (10ⁿ) metres, with corresponding frequency of 3×10⁸⁻ⁿ hertz, and each covering a decade of frequency or wavelength. Each of these bands has a traditional name.

Of course, there is more to this ‘story’ and some other world-renowned organizations also had a hand in the matter. US Institute of Electrical and Electronic Engineers (IEEE) has been quite productive and made a very salient contribution by introducing further classification of microwave range. Thanks to IEEE the frequency bands in the microwave range are designated by letters. This classification has also become widely used standard for radar bands.

This convention began around World War 2 with military designations for frequencies used in radar, which was the first application of microwaves. It happened so there are several incompatible naming systems for microwave bands, and even within a given system the exact frequency range designated by a letter may vary somewhat between different application areas.

Of course other high-profile organizations like EU, NATO, US ECM have also made their contributions by introducing their view on classification frequency designations. The table below provides a brief comparison between classification and shows the ‘overlap’ areas.

Some of our customers often use various terms associated with radio frequency bands and RF terminology in general, especially with reference to our terahertz generators (THz sources). This calls for a brief description of the Waveguide frequency bands established as standard among experts.

Terasense can offer THz sources that fit into E band, W band, F band and D band. For further details please visit our web-page dedicated to THz generators.