2.2. Electromagnetic Spectrum

The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies [64].


Fig. 2.3 : Electromagnetic Spectrum.

2.2.1. Radio Spectrum

International Telecommunication Union (ITU) divides the radio spectrum into 12 bands, each beginning at a wavelength which is a power of ten (10:sup:n) metres, with corresponding frequency of 3×10:sup:8−n hertz, and each covering a decade of frequency or wavelength [68].

Table 2.1 Radio spectrum bands and example uses.
Band name Abbreviation Frequency Wavelength Example Uses
Extremely low frequency ELF 3–30 Hz 100,000–10,000 km Communication with submarines
Super low frequency SLF 30–300 Hz 10,000–1,000 km Communication with submarines
Ultra low frequency ULF 300–3,000 Hz 1,000–100 km Submarine communication, communication within mines
Very low frequency VLF 3–30 kHz 100–10 km Navigation, time signals, submarine communication, wireless heart rate monitors, geophysics
Low frequency LF 30–300 kHz 10–1 km Navigation, time signals, AM longwave broadcasting (Europe and parts of Asia), RFID, amateur radio
Medium frequency MF 300–3,000 kHz 1,000–100 m AM (medium-wave) broadcasts, amateur radio, avalanche beacons
High frequency HF 3–30 MHz 100–10 m Shortwave broadcasts, citizens band radio, amateur radio and over-the-horizon aviation communications, RFID, over-the-horizon radar, automatic link establishment (ALE) / near-vertical incidence skywave(NVIS) radio communications, marine and mobile radio telephony
Very high frequency VHF 30–300 MHz 10–1 m FM, television broadcasts, line-of-sight ground-to-aircraft and aircraft-to-aircraft communications, land mobile and maritime mobile communications, amateur radio, weather radio
Ultra high frequency UHF 300–3,000 MHz 1–0.1 m Television broadcasts, microwave oven, microwavedevices/communications, radio astronomy, mobile phones, wireless LAN, Bluetooth, ZigBee, GPS and two-way radios such as land mobile, FRS and GMRSradios, amateur radio, satellite radio, Remote control Systems, ADSB
Super high frequency SHF 3–30 GHz 100–10 mm Radio astronomy, microwave devices/communications, wireless LAN, DSRC, most modern radars, communications satellites, cable and satellite television broadcasting, DBS, amateur radio, satellite radio
Extremely high frequency EHF 30–300 GHz 10–1 mm Radio astronomy, high-frequency microwave radio relay, microwave remote sensing, amateur radio, directed-energy weapon, millimeter wave scanner, wireless LAN (802.11ad)
Terahertz or Tremendously high frequency THz or THF 300–3,000 GHz 1–0.1 mm Experimental medical imaging to replace X-rays, ultrafast molecular dynamics, condensed-matter physics, terahertz time-domain spectroscopy, terahertz computing/communications, remote sensing