- Industry: Telecommunications
- Number of terms: 29235
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ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the information, entertainment and communications industry.
Of an antenna, the lowest frequency at which the antenna resonates without the addition of any inductance or capacitance.
Industry:Telecommunications
Of an antenna, the ratio of (a) 4 times the radiance, i.e., power radiated per unit solid angle (watts per steradian,) in a given direction to (b) the total power, i.e., the power radiated to 4 steradians. Note 1: The directive gain is usually expressed in dB. Note 2: The directive gain is relative to an isotropic antenna. Note 3: The power radiated to 4 steradians is the total power radiated by the antenna because 4 steradians constitute an entire sphere. 2. Of an antenna, for a given direction, the ratio of the radiance, i.e., the radiation intensity, produced in the given direction to the average value of the radiance in all directions. Note 1: If the direction is not specified, the direction of maximum radiance is assumed. Note 2: The directive gain is usually expressed in dB.
Industry:Telecommunications
Of an electrical or electromagnetic signal, its speed in a physical medium such as a coaxial cable or optical fiber.
Industry:Telecommunications
Of an electromagnetic beam, along any specified line that (a) intersects the beam axis and (b) lies in any specified plane normal to the beam axis, the distance between the two diametrically opposite points at which the irradiance is a specified fraction, e. G. , ½ or 1/, of the beam's peak irradiance. Note 1: Beam diameter is usually used to characterize electromagnetic beams in the optical regime, and occasionally in the microwave regime, i.e., cases in which the aperture from which the beam emerges is very large with respect to the wavelength. Note 2: Beam diameter usually refers to a beam of circular cross section, but not necessarily so. A beam may, for example, have an elliptical cross section, in which case the orientation of the beam diameter must be specified, e. G. , with respect to the major or minor axis of the elliptical cross section.
Industry:Telecommunications
Of an electromagnetic beam, in any plane that intersects the beam axis, the increase in beam diameter with distance from the aperture from which the beam emerges. Note 1: Beam divergence is usually used to characterize electromagnetic beams in the optical regime, i.e., cases in which the aperture from which the beam emerges is very large with respect to the wavelength. Note 2: Beam divergence usually refers to a beam of circular cross section, but not necessarily so. A beam may, for example, have an elliptical cross section, in which case the orientation of the beam divergence must be specified, e. G. , with respect to the major or minor axis of the elliptical cross section.
Industry:Telecommunications
Of an electromagnetic source, especially in the optical regime, the hue or wavelength (spectral content) expressed or specified as the hypothetical wavelength (s) emitted by an ideal blackbody having an absolute temperature of n kelvins (n K. ) Note 1: Higher numbers indicate hues in or toward the blue; lower numbers indicate hues in or toward the red. Note 2: Examples of color temperature are approximately 5000 K to 5500 K (daylight,) approximately 4100 K (fluorescent lighting,) and approximately 2800 K (incandescent. ) Note 3: Color temperature is commonly used to characterize ambient lighting or lighting employed for photographic purposes.
Industry:Telecommunications
Of an electromagnetic wave having elliptical polarization, the ratio of the magnitudes of the major axis and the minor axis of the ellipse described by the electric field vector.
Industry:Telecommunications
Of an electromagnetic wave propagating in a material medium, scattering caused by refractive-index inhomogeneities that are small compared to the wavelength. Note 1: Rayleigh scattering losses vary as the reciprocal of the fourth power of the wavelength. Note 2: Ionospheric scattering is caused partly by Rayleigh scattering.
Industry:Telecommunications
Of an electromagnetic wave, confinement of the E-field vector or H-field vector to a given plane. Note: Historically, the orientation of a polarized electromagnetic wave has been defined in the optical regime by the orientation of the electric vector, and in the radio regime, by the orientation of the magnetic vector. Synonym plane polarization.
Industry:Telecommunications
Of an electromagnetic wave, confinement of the E-field vector or H-field vector to a given plane. Note: Historically, the orientation of a polarized electromagnetic wave has been defined in the optical regime by the orientation of the electric vector, and in the radio regime, by the orientation of the magnetic vector. Synonym plane polarization.
Industry:Telecommunications
