Ultra high frequencyEU / NATO / US ECM ABCDEFGHIJKLMNIEEE HFVHFUHFLSCXKuKKaVWmm Other TV and radioIIIIIIIVVVIUltra 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 (one decimeter). Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range.
High frequencyEU / NATO / US ECM ABCDEFGHIJKLMNIEEE HFVHFUHFLSCXKuKKaVWmm Other TV and radioIIIIIIIVVVIHigh frequency (HF) is the ITU designation for the band of radio waves with frequency 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 (ten to one hundred meters).
Line-of-sight propagationLine-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. Electromagnetic transmission includes light emissions traveling in a straight line.
Radio waveRadio waves (formerly called Hertzian waves) are a type of electromagnetic radiation with the lowest frequencies and the longest wavelengths in the electromagnetic spectrum, typically with frequencies below 300 gigahertz (GHz) and wavelengths greater than 1 millimeter (3⁄64 inch), about the diameter of a grain of rice. Radio waves with frequencies above about 1 GHz and wavelengths shorter than 30 centimeters are called microwaves.
Digital Audio BroadcastingDigital radio standardOfficial DAB+ logoOfficial DAB logo (1990s–2018)A Pure DAB receiverDigital Audio Broadcasting (DAB) is a digital radiostandard for broadcastingdigital audio radio services in many countries around the world, defined, supported, marketed and promoted by the WorldDAB organization.
Radio frequencyRadio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. These are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves, so they are used in radio technology, among other uses.
HorizonMost commonly, the horizon is the border between the surface of a celestial body and its sky when viewed from the perspective of an observer on or above the surface of the celestial body. This concept is further refined as: The true or geometric horizon, which an observer would see if there was no alteration from refraction or from obstruction by intervening objects. The geometric horizon assumes a spherical earth.
RefractionIn physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomenon, but other waves such as sound waves and water waves also experience refraction.
International Telecommunication UnionSpecialized agency of the United NationsThe International Telecommunication Union (ITU) is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Union, the first formal and permanent international organization. The organization significantly predates the UN, making it the oldest UN agency.
FM broadcastingFM broadcasting is a radio broadcasting method that uses frequency modulation (FM) transmissions. In November 1919, Hans Idzerda began broadcasts, using narrow-band FM, over station PCGG, located at The Hague in the Netherlands. However, most early broadcasting stations instead employed Amplitude Modulation (AM) transmissions. In 1933, American engineer Edwin Armstrong began development of wide-band FM.
HertzThe hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base units is 1/s or s−1, meaning that one hertz is one per second or the reciprocal of one second. It is used only in the case of periodic events.
Electromagnetic radiationPhysical model of propagating energyA linearly polarized electromagnetic wave going in the z-axis, with E denoting the electric field and perpendicular B denoting magnetic fieldIn physics, electromagnetic radiation (EMR) or an electromagnetic wave (EMW) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space.*As an Amazon Associate I earn from qualifying purchases.