IEEE 211-2018 pdf download
IEEE 211-2018 pdf download.IEEE Standard Definitions of Terms for Radio Waves Propagation.
depolarization: A process by which the polarization state of a wave is altered.
diamagnetic material: A material that is weakly repelled by a magnetic field that is applied on it. Diamagnetic materials are not magnetized in the absence of an applied static magnetic field and have a small negative magnetic susceptibility. All materials exhibit some degree of diamagnetism, but in magnetic materials the diamagnetic effects are very weak in comparison to other effects.
dielectric constant: See: relative complex perniittivity (Cr).
diffracted wave: An electromagnetic wave that has been modified by an obstacle or spatial inhomogeneity in
the medium by means other than reflection or refraction.
diffraction: The deviation of the direction of energy flow of a wave, not attributable to reflection or refraction, when it passes an obstacle, a restricted aperture. or other inhotnogenieties in a medium.
diffuse field: For random media, the non-coherent component of the scattered field. NOTE The diffuse electromagnetic field has a zero average value, (i.e., it is a zero-mean process). diffuse intensity: Power density associated with the diffuse field.
diffuse reflection: See: diffuse scattering.
diffuse scattering: The generation of non-coherent (diffuse) fields caused by scattering of an incident electromagnetic wave by a random rough surface or a medium randomly varying with time and/or space.
diffusion approximation: For wave propagation in lossy media, it corresponds to neglecting the displacement current.
direct wave: A wave propagated over an unobstructed ray path from a source to a point.
direction of polarization: (of an elliptically polarized wave). The direction of the major axis of the electric vector ellipse. See also: elliptically polarized wave.
direction of propagation: At any point in a medium, the direction of the time-averaged energy flow. See also:
Poynting vector.
I)irichlet boundary condition: A boundary condition applied to the solution of a partial differential equation in which the function is specified on the boundary.
NOTE—When applied to the wave equation for electromagnetic fields, it requires continuity of the tangential field components across the boundary.
dispersion: (of a wave). The variation of the phase velocity with frequency.
dispersion relation: The functional relationship between the angular frequency, w, and the wave vector, k, for waves in a source-free medium. For a dispersionless medium, the components of k are linearly proportional to w.
ducting: Guided propagation of radio waves inside an atmospheric or tropospheric radio frequency (RF) duct. See also: atmospheric radio frequency (RF) duct.
E layer: An ionized layer in the E region. The ionization within the E region is highly correlated with the incident solar flux. Therefore, the normal E layer is present oniy during daytime.
E region: The region of the terrestrial ionosphere between about 90 km and 150 km altitude.
edge diffraction: Diffraction by a transverse obstacle with a relatively sharp profile, located between the transmission and reception points. Diffraction over a very sharp profile is frequently called knife-edge diffraction.
effective medium: The replacement of an inhomogeneous medium by an equivalent homogeneous medium having complex constitutive parameters derived from the propagation of the coherent (i.e., mean) field in the actual medium. The equivalent medium describes only the coherent field.
effective radius of the Earth: An effective value for the radius of the Earth that is used in place of the actual radius to correct approximately for standard annospheric refraction. See also: k-factor; refractive index gradient.
NOTE—Under conditions of standard refraction, the effective radius of the Earth is 8.5 x 106 m, or 4/3 the geometrical radius.
EHF: See: extremely high frequency (KHF).
eikonal: A function that describes the phase propagation of a time harmonic field.
electric displacement: See: electric flux density ( D).
electric held (F): The electric force that acts on a unit electric charge independent of the velocity 01 that charge.
