Radio spectrum

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The radio spectrum is the part of the electromagnetic spectrum with frequencies from 30  Hertz to 300  GHz. Electromagnetic waves in this frequency range, called radio waves, are extremely widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU). [1]

The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.

Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. For example: if a newborn baby's heart beats at a frequency of 120 times a minute, its period—the time interval between beats—is half a second. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light.

Hertz SI unit for frequency

The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (103 Hz, kHz), megahertz (106 Hz, MHz), gigahertz (109 Hz, GHz), terahertz (1012 Hz, THz), petahertz (1015 Hz, PHz), and exahertz (1018 Hz, EHz).

Contents

Different parts of the radio spectrum are allocated by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). [2] In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum). [3] Because it is a fixed resource which is in demand by an increasing number of users, the radio spectrum has become increasingly congested in recent decades, and the need to utilize it more effectively is driving modern telecommunications innovations such as trunked radio systems, spread spectrum (ultra-wideband) transmission, frequency reuse, dynamic spectrum management, frequency pooling, and cognitive radio.

The ITU Radio Regulations regulates on law of nations scale radiocommunication services and the utilisation of radio frequencies. It is the supplementation to the Constitution and Convention of the International Telecommunication Union. In line to the ITU Constitution and Convention and the ITU International Telecommunication Regulations (ITR), this ITU Radio Regulations belong to the basic documents of the International Telecommunication Union. The ITU Radio Regulations comprise and regulate the part of the allocated electromagnetic spectrum from 9 kHz to 275 GHz.

Trunked radio system class of a radio system

A trunked radio system is two-way radio system that uses a control channel to automatically direct radio traffic. Two-way radio systems are either trunked or conventional, where conventional is manually directed by the radio user.

Spread spectrum

In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of secure communications, increasing resistance to natural interference, noise and jamming, to prevent detection, and to limit power flux density.

Bands

A radio band is a small contiguous section of the radio spectrum frequencies, in which channels are usually used or set aside for the same purpose. To prevent interference and allow for efficient use of the radio spectrum, similar services are allocated in bands. For example, broadcasting, mobile radio, or navigation devices, will be allocated in non-overlapping ranges of frequencies.

Communication channel refers either to a physical transmission medium such as a wire, or to a logical connection

A communication channel or simply channel refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel in telecommunications and computer networking. A channel is used to convey an information signal, for example a digital bit stream, from one or several senders to one or several receivers. A channel has a certain capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second.

For each of these bands the ITU has a bandplan which dictates how it is to be used and shared, to avoid interference and to set protocol for the compatibility of transmitters and receivers. [4]

A bandplan or band plan is a plan for using a particular band of radio frequencies, that are a portion of the electromagnetic spectrum. Each bandplan defines the frequency range to be included, how channels are to be defined, and what will be carried on those channels. Typical definitions set forth in a bandplan are:

Co-channel interference or CCI is crosstalk from two different radio transmitters using the same channel. Co-channel interference can be caused by many factors from weather conditions to administrative and design issues. Co-channel interference may be controlled by various radio resource management schemes.

Transmitter Electronic device that emits radio waves

In electronics and telecommunications, a transmitter or radio transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves.

ITU

As a matter of convention, the ITU divides the radio spectrum into 12 bands, 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. For example, the term high frequency (HF) designates the wavelength range from 100 to 10 metres, corresponding to a frequency range of 3 MHz to 30 MHz. This is just a naming convention and is not related to allocation; the ITU further divides each band into subbands allocated to different uses. Above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that the atmosphere is effectively opaque, until it becomes transparent again in the near-infrared and optical window frequency ranges.

Wavelength spatial period of the wave—the distance over which the waves shape repeats, and thus the inverse of the spatial frequency

In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is thus the inverse of the spatial frequency. Wavelength is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. Wavelength is commonly designated by the Greek letter lambda (λ). The term wavelength is also sometimes applied to modulated waves, and to the sinusoidal envelopes of modulated waves or waves formed by interference of several sinusoids.

High frequency frequencies between 3-30MHz

High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters. Frequencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band. The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio. Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as "skip" or "skywave" propagation – these frequencies are suitable for long-distance communication across intercontinental distances and for mountainous terrains which prevent line-of-sight communications. The band is used by international shortwave broadcasting stations (2.31–25.82 MHz), aviation communication, government time stations, weather stations, amateur radio and citizens band services, among other uses.

Electromagnetic radiation form of energy emitted and absorbed by charged particles, which exhibits wave-like behavior as it travels through space

In physics, electromagnetic radiation refers to the waves of the electromagnetic field, propagating (radiating) through space, carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

These ITU radio bands are defined in the ITU Radio Regulations. Article 2, provision No. 2.1 states that "the radio spectrum shall be subdivided into nine frequency bands, which shall be designated by progressive whole numbers in accordance with the following table [5] ".

The table originated with a recommendation of the IVth CCIR meeting, held in Bucharest in 1937, and was approved by the International Radio Conference held at Atlantic City, NJ in 1947. The idea to give each band a number, in which the number is the logarithm of the approximate geometric mean of the upper and lower band limits in Hz, originated with B.C. Fleming-Williams, who suggested it in a letter to the editor of Wireless Engineer in 1942. (For example, the approximate geometric mean of Band 7 is 10 MHz, or 107 Hz.) [6]

Band nameAbbreviationITU band numberFrequency and WavelengthExample Uses
Extremely low frequency ELF13–30 Hz
100,000–10,000 km
Communication with submarines
Super low frequency SLF230–300 Hz
10,000–1,000 km
Communication with submarines
Ultra low frequency ULF3300–3,000 Hz
1,000–100 km
Submarine communication, communication within mines
Very low frequency VLF43–30 kHz
100–10 km
Navigation, time signals, submarine communication, wireless heart rate monitors, geophysics
Low frequency LF530–300 kHz
10–1 km
Navigation, time signals, AM longwave broadcasting (Europe and parts of Asia), RFID, amateur radio
Medium frequency MF6300–3,000 kHz
1,000–100 m
AM (medium-wave) broadcasts, amateur radio, avalanche beacons
High frequency HF73–30 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 VHF830–300 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 UHF9300–3,000 MHz
1–0.1 m
Television broadcasts, microwave oven, microwave devices/communications, radio astronomy, mobile phones, wireless LAN, Bluetooth, ZigBee, GPS and two-way radios such as land mobile, FRS and GMRS radios, amateur radio, satellite radio, Remote control Systems, ADSB
Super high frequency SHF103–30 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 EHF1130–300 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 THF12300–3,000 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,

IEEE radar bands

Frequency bands in the microwave range are designated by letters. This convention began around World War 2 with military designations for frequencies used in radar, which was the first application of microwaves. Unfortunately 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. One widely used standard is the IEEE radar bands established by the US Institute of Electrical and Electronic Engineers.


Radar-frequency bands according to IEEE standard [7]
Band
designation
Frequency rangeExplanation of meaning of letters
HF 0.003 to 0.03 GHzHigh Frequency [8]
VHF 0.03 to 0.3 GHzVery High Frequency [8]
UHF 0.3 to 1 GHzUltra High Frequency [8]
L 1 to 2 GHzLong wave
S 2 to 4 GHzShort wave
C 4 to 8 GHzCompromise between S and X
X 8 to 12 GHzUsed in WW II for fire control, X for cross (as in crosshair). Exotic. [9]
Ku 12 to 18 GHzKurz-under
K 18 to 27 GHzKurz (German for "short")
Ka 27 to 40 GHzKurz-above
V 40 to 75 GHz
W 75 to 110 GHzW follows V in the alphabet [ citation needed ]
mm or G 110 to 300 GHz [note 1] Millimeter [7]
  1. The designation mm is also used to refer to the range from 30 to 300 GHz. [7]

EU, NATO, US ECM frequency designations

NATO LETTER BAND DESIGNATION [10] [9] [11] BROADCASTING
BAND
DESIGNATION
NEW NOMENCLATUREOLD NOMENCLATURE
BANDFREQUENCY (MHz)BANDFREQUENCY (MHz)
A 0 – 250I 100 – 150Band I
47 – 68 MHz (TV)
Band II
87.5 – 108 MHz (FM)
G 150 – 225Band III
174 – 230 MHz (TV)
B 250 – 500P 225 – 390
C 500 – 1 000L 390 – 1 550Band IV
470 – 582 MHz (TV)
Band V
582 – 862 MHz (TV)
D 1 000 – 2 000S 1 550 – 3 900
E 2 000 – 3 000
F 3 000 – 4 000
G 4 000 – 6 000C 3 900 – 6 200
H 6 000 – 8 000X 6 200 – 10 900
I 8 000 – 10 000
J 10 000 – 20 000Ku10 900 – 20 000
K 20 000 – 40 000Ka20 000 – 36 000
L 40 000 – 60 000Q 36 000 – 46 000
V 46 000 – 56 000
M 60 000 – 100 000W 56 000 – 100 000
US- MILITARY / SACLANT
N 100 000 – 200 000
O 100 000 – 200 000

Waveguide frequency bands

BandFrequency range [12]
R band 1.70 to 2.60 GHz
D band2.20 to 3.30 GHz
S band2.60 to 3.95 GHz
E band3.30 to 4.90 GHz
G band3.95 to 5.85 GHz
F band4.90 to 7.05 GHz
C band5.85 to 8.20 GHz
H band7.05 to 10.10 GHz
X band 8.2 to 12.4 GHz
Ku band 12.4 to 18.0 GHz
K band 18.0 to 26.5 GHz
Ka band 26.5 to 40.0 GHz
Q band 33 to 50 GHz
U band 40 to 60 GHz
V band 40 to 75 GHz
E band 60 to 90 GHz
W band 75 to 110 GHz
F band 90 to 140 GHz
D band 110 to 170 GHz
Y band 325 to 500 GHz

Comparison of radio band designation standards

Comparison of frequency band designations Frq Band Comparison.png
Comparison of frequency band designations
FrequencyIEEE [7] EU,
NATO,
US ECM
ITU
no.abbr.
A  
3 Hz 1 ELF
30 Hz 2 SLF
300 Hz 3 ULF
3 kHz 4 VLF
30 kHz 5 LF
300 kHz 6 MF
3 MHz HF 7 HF
30 MHz VHF 8 VHF
250 MHz B
300 MHz UHF 9 UHF
500 MHz C
1 GHz L D
2 GHz S E
3 GHz F 10 SHF
4 GHz C G
6 GHz H
8 GHz X I
10 GHz J
12 GHz Ku
18 GHz K
20 GHz K
27 GHz Ka
30 GHz 11 EHF
40 GHz V L
60 GHz M
75 GHz W
100 GHz
110 GHz mm
300 GHz 12 THF
3 THz 

Applications

Broadcasting

Broadcast frequencies:

Designations for television and FM radio broadcast frequencies vary between countries, see Television channel frequencies and FM broadcast band. Since VHF and UHF frequencies are desirable for many uses in urban areas, in North America some parts of the former television broadcasting band have been reassigned to cellular phone and various land mobile communications systems. Even within the allocation still dedicated to television, TV-band devices use channels without local broadcasters.

The Apex band in the United States was a pre-WWII allocation for VHF audio broadcasting; it was made obsolete after the introduction of FM broadcasting.

Air band

Airband refers to VHF frequencies 118 to 137 MHz, used for navigation and voice communication with aircraft. Trans-oceanic aircraft also carry HF radio and satellite transceivers.

Marine band

The greatest incentive for development of radio was the need to communicate with ships out of visual range of shore. From the very early days of radio, large oceangoing vessels carried powerful long-wave and medium-wave transmitters. High-frequency allocations are still designated for ships, although satellite systems have taken over some of the safety applications previously served by 500 kHz and other frequencies. 2182 kHz is a medium-wave frequency still used for marine emergency communication.

Marine VHF radio is used in coastal waters and relatively short-range communication between vessels and to shore stations. Radios are channelized, with different channels used for different purposes; marine Channel 16 is used for calling and emergencies.

Amateur radio frequencies

Amateur radio frequency allocations vary around the world. Several bands are common for amateurs worldwide, usually in the HF part of the spectrum. Other bands are national or regional allocations only due to differing allocations for other services, especially in the VHF and UHF parts of the radio spectrum.

Citizens' band and personal radio services

Citizens' band radio is allocated in many countries, using channelized radios in the upper HF part of the spectrum (around 27 MHz). It is used for personal, small business and hobby purposes. Other frequency allocations are used for similar services in different jurisdictions, for example UHF CB is allocated in Australia. A wide range of personal radio services exist around the world, usually emphasizing short-range communication between individuals or for small businesses, simplified or no license requirements, and usually FM transceivers using around 1 watt or less.

Industrial, scientific, medical

The ISM bands were initially reserved for non-communications uses of RF energy, such as microwave ovens, radio-frequency heating, and similar purposes. However, in recent years the largest use of these bands has been by short-range low-power communications systems, since users do not have to hold a radio operator's license. Cordless telephones, wireless computer networks, Bluetooth devices, and garage door openers all use the ISM bands. ISM devices do not have regulatory protection against interference from other users of the band.

Land mobile bands

Bands of frequencies, especially in the VHF and UHF parts of the spectrum, are allocated for communication between fixed base stations and land mobile vehicle-mounted or portable transceivers. In the United States these services are informally known as business band radio. See also Professional mobile radio.

Police radio and other public safety services such as fire departments and ambulances are generally found in the VHF and UHF parts of the spectrum. Trunking systems are often used to make most efficient use of the limited number of frequencies available.

The demand for mobile telephone service has led to large blocks of radio spectrum allocated to cellular frequencies.

Radio control

Reliable radio control uses bands dedicated to the purpose. Radio-controlled toys may use portions of unlicensed spectrum in the 27 MHz or 49 MHz bands, but more costly aircraft, boat, or land vehicle models use dedicated radio control frequencies near 72 MHz to avoid interference by unlicensed uses. The 21st century has seen a move to 2.4 gigahertz spread spectrum RC control systems.

Licensed amateur radio operators use portions of the 6-meter band in North America. Industrial remote control of cranes or railway locomotives use assigned frequencies that vary by area.

Radar

Radar applications use relatively high power pulse transmitters and sensitive receivers, so radar is operated on bands not used for other purposes. Most radar bands are in the microwave part of the spectrum, although certain important applications for meteorology make use of powerful transmitters in the UHF band. Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 GHz to as low as 3 kHz, though some definitions describe waves above 1 or 3 GHz as microwaves, or include waves of any lower frequency. At 300 GHz, the corresponding wavelength is 1 mm (0.039 in), and at 3 kHz is 100 km (62 mi). Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are generated by lightning, or by astronomical objects.

Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, computer networks and innumerable other applications. Radio waves are generated by radio transmitters and received by radio receivers. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves can diffract around obstacles like mountains and follow the contour of the earth (ground waves), shorter waves can reflect off the ionosphere and return to earth beyond the horizon (skywaves), while much shorter wavelengths bend or diffract very little and travel on a line of sight, so their propagation distances are limited to the visual horizon.

To prevent interference between different users, the artificial generation and use of radio waves is strictly regulated by law, coordinated by an international body called the International Telecommunications Union (ITU), which defines radio waves as "electromagnetic waves of frequencies arbitrarily lower than 3 000 GHz, propagated in space without artificial guide".[1] The radio spectrum is divided into a number of radio bands on the basis of frequency, allocated to different uses

See also

Notes

  1. ITU Radio Regulations – Article 1, Definitions of Radio Services, Article 1.2 Administration: Any governmental department or service responsible for discharging the obligations undertaken in the Constitution of the International Telecommunication Union, in the Convention of the International Telecommunication Union and in the Administrative Regulations (CS 1002)
  2. International Telecommunication Union´s Radio Regulations, Edition of 2012.
  3. Colin Robinson (2003). Competition and regulation in utility markets. Edward Elgar Publishing. p. 175. ISBN   978-1-84376-230-0.
  4. See detail of bands:
  5. ITU Radio Regulations, Volume 1, Article 2; Edition of 2008. Available online at "Archived copy". Archived from the original on 2011-10-01. Retrieved 2012-01-12.CS1 maint: Archived copy as title (link)
  6. Booth, C.F. (1949). "Nomenclature of Frequencies". The Post Office Electrical Engineers' Journal . 42 (1): 47–48.
  7. 1 2 3 4 5 IEEE Std 521-2002 Standard Letter Designations for Radar-Frequency Bands.
  8. 1 2 3 Table 2 in [7]
  9. 1 2 Norman Friedman (2006). The Naval Institute Guide to World Naval Weapon Systems. Naval Institute Press. pp. xiii. ISBN   978-1-55750-262-9.
  10. Leonid A. Belov; Sergey M. Smolskiy; Victor N. Kochemasov (2012). Handbook of RF, Microwave, and Millimeter-Wave Components. Artech House. pp. 27–28. ISBN   978-1-60807-209-5.
  11. NATO Allied Radio Frequency Agency (ARFA) HANDBOOK – VOLUME I; PART IV – APPENDICES, … G-2, … NOMENCLATURE OF THE FREQUENCY AND WAVELENTH BANDS USED IN RADIOCOMMUNCATION.
  12. www.microwaves101.com "Waveguide frequency bands and interior dimensions"

Related Research Articles

The industrial, scientific and medical (ISM) radio bands are radio bands reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than telecommunications. Examples of applications in these bands include radio-frequency process heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication using the same frequency, so these devices were limited to certain bands of frequencies. In general, communications equipment operating in these bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation.

Microwave form of electromagnetic radiation

Microwaves are a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter; with frequencies between 300 MHz (1 m) and 300 GHz (1 mm). Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF bands. A more common definition in radio engineering is the range between 1 and 100 GHz. In all cases, microwaves include the entire SHF band at minimum. Frequencies in the microwave range are often referred to by their IEEE radar band designations: S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations.

Very high frequency class of radio waves

Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).

The Ku band is the portion of the electromagnetic spectrum in the microwave range of frequencies from 12 to 18 gigahertz (GHz). The symbol is short for "K-under", because it is the lower part of the original NATO K band, which was split into three bands because of the presence of the atmospheric water vapor resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12-18 GHz according to the formal definition of radar frequency band nomenclature in IEEE Standard 521-2002.

Ultra high frequency radio waves

Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter. Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications.

Medium frequency Frequencies between 300 kHz to 3 MHz

Medium frequency (MF) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometer. Frequencies immediately below MF are denoted low frequency (LF), while the first band of higher frequencies is known as high frequency (HF). MF is mostly used for AM radio broadcasting, navigational radio beacons, maritime ship-to-shore communication, and transoceanic air traffic control.

Radio propagation behavior of radio waves as they travel, or are propagated, from one point to another, or into various parts of the atmosphere

Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for international shortwave broadcasters, to designing reliable mobile telephone systems, to radio navigation, to operation of radar systems.

The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional boundary between the UHF and SHF bands at 3.0 GHz. The S band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, especially those used by NASA to communicate with the Space Shuttle and the International Space Station. The 10 cm radar short-band ranges roughly from 1.55 to 5.2 GHz. The S band also contains the 2.4–2.483 GHz ISM band, widely used for low power unlicensed microwave devices such as cordless phones, wireless headphones (Bluetooth), wireless networking (WiFi), garage door openers, keyless vehicle locks, baby monitors as well as for medical diathermy machines and microwave ovens. India’s regional satellite navigation network (IRNSS) broadcasts on 2.483778 to 2.500278 GHz.

The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approximately 7.0 to 11.2 GHz. In radar engineering, the frequency range is specified by the IEEE at 8.0 to 12.0 GHz. The X band is used for radar, satellite communication, and wireless computer networks.

Extremely high frequency radio waves

Extremely high frequency (EHF) is the International Telecommunication Union (ITU) designation for the band of radio frequencies in the electromagnetic spectrum from 30 to 300 gigahertz (GHz). It lies between the super high frequency band, and the far infrared band, the lower part of which is also referred to as the terahertz gap. Radio waves in this band have wavelengths from ten to one millimetre, so it is also called the millimetre band and radiation in this band is called millimetre waves, sometimes abbreviated MMW or mmW. Millimetre-length electromagnetic waves were first investigated in the 1890s by Indian scientist Jagadish Chandra Bose.

The 70-centimeter or 440 MHz band is a portion of the UHF radio spectrum internationally allocated to amateur radio and amateur satellite use. The ITU amateur radio allocation is from 430 to 440 MHz; however, some countries, such as the United States, allocate hams 420 to 450 MHz. Amateur satellites are only allocated a small portion of the band, 435 to 438 MHz, on a non-interference basis. The band is usually shared with other radio services, most commonly government radar systems, such as PAVE PAWS.

6-meter band amateur radio frequency allocations

The 6-meter band is the lowest portion of the very high frequency (VHF) radio spectrum allocated to amateur radio use. The term refers to the average signal wavelength of 6 meters.

Shortwave bands are frequency allocations for use within the shortwave radio spectrum. They are the primary medium for applications such as maritime communications, international broadcasting and worldwide amateur radio activity because they take advantage of ionospheric skip propagation to send data around the world. The bands are conventionally stated in wavelength, measured in metres. Propagation behavior on the shortwave bands depends on the time of day, the season and the level of solar activity.

The 23 centimeter, 1200 MHz or 1.2 GHz band is a portion of the UHF (microwave) radio spectrum internationally allocated to amateur radio and amateur satellite use on a secondary basis. The amateur radio band is between 1240 MHz and 1300 MHz. The amateur satellite band is between 1260 MHz and 1270 MHz, and its use by satellite operations is only for up-links on a non-interference basis to other radio users. The allocations are the same in all three ITU regions.

The 5 centimeter or 5 GHz band is a portion of the SHF (microwave) radio spectrum internationally allocated to amateur radio and amateur satellite use on a secondary basis. In ITU regions 1 and 3, the amateur radio band is between 5,650 MHz and 5,850 MHz. In ITU region 2, the amateur radio band is between 5,650 MHz and 5,925 MHz. The amateur satellite service is allocated 5,830 to 5,850 MHz, for down-links only on a secondary basis, and it is also allocated 5,650 to 5,670 MHz, for up-links only on a non-interference basis to other users. Amateur stations must accept harmful interference from ISM users operating in the band. The band is within the IEEE C Band spectrum.

The 13 centimeter, 2.3 GHz or 2.4 GHz band is a portion of the UHF (microwave) radio spectrum internationally allocated to amateur radio and amateur satellite use on a secondary basis. The amateur radio band is between 2300 MHz and 2450 MHz. The amateur satellite band is between 2400 MHz and 2450 MHz, and its use by satellite operations is on a non-interference basis to other radio users. The license privileges of amateur radio operators include the use of frequencies and a wide variety of modes within these ranges for telecommunication. The allocations are the same in all three ITU Regions.

Non-ionizing radiation electromagnetic radiation that does not carry enough energy per quantum to ionize atoms or molecules

Non-ionizingradiation refers to any type of electromagnetic radiation that does not carry enough energy per quantum to ionize atoms or molecules—that is, to completely remove an electron from an atom or molecule. Instead of producing charged ions when passing through matter, non-ionizing electromagnetic radiation has sufficient energy only for excitation, the movement of an electron to a higher energy state. Ionizing radiation which has a higher frequency and shorter wavelength than nonionizing radiation, has many uses but can be a health hazard; exposure to it can cause burns, radiation sickness, cancer, and genetic damage. Using ionizing radiation requires elaborate radiological protection measures which in general are not required with nonionizing radiation.

The 9-centimeter band is a portion of the SHF (microwave) radio spectrum internationally allocated to amateur radio and amateur satellite use. The amateur radio band, in ITU regions 1 and 2, is between 3,300 MHz and 3,500 MHz, and it is available only on a secondary basis. The amateur satellite band is between 3,400 MHz and 3,410 MHz, and it is only available in ITU Regions 1 and 2, on a non-interference basis to other users. In Germany and Israel, the band 3,400 - 3,475 MHz is also allocated to the amateur service on a secondary basis.

References