anomalous propagation

A condition prevalent in the troposphere that results in VHF (very high frequency) and UHF (ultrahigh frequency) transmissions being received at very long distances. This is because certain layers of troposphere are bound above and below by layers that have different refractive indices. They confine and propagate abnormally high proportions of VHF and UHF radiation, giving freak long-distance communications and radar pickup ranges. The thickness of such layers is seldom more than 300 ft (100 m).
The reflected signal in the second case will travel over a longer distance than in the first case.

Aviation dictionary. 2014.

Look at other dictionaries:

  • Anomalous propagation — In Radio: Anomalous propagation includes different forms of electromagnetic wave propagation that are not encountered in a standard atmosphere. While technically the term includes propagation with larger losses than in standard atmosphere, in… …   Wikipedia

  • Non-line-of-sight propagation — Non line of sight (NLOS) or near line of sight is a term used to describe radio transmission across a path that is partially obstructed, usually by a physical object in the innermost Fresnel zone. Many types of radio transmissions depend, to… …   Wikipedia

  • Line-of-sight propagation — refers to electro magnetic radiation including light emissions traveling in a straight line. The rays or waves are diffracted, refracted, reflected, or absorbed by atmosphere and obstructions with material and generally cannot travel over the… …   Wikipedia

  • List of radio propagation topics — This is a list of radio propagation terms. NOTOC A a index A index aa index active prominence active prominence region (APR) active region active surge region (ASR) active dark filament (ADF) AE index Air Force Geophysics Laboratory (AFGL) arch… …   Wikipedia

  • duct propagation — A layer of troposphere bounded above and below by layers that have different refractive index, which confines and propagates an abnormally high proportion of VHF (very high frequency) and UHF (ultrahigh frequency) radiation. This results in freak …   Aviation dictionary

  • Weather radar — in Norman, Oklahoma with rainshaft …   Wikipedia

  • Metamaterial antenna — This Z antenna tested at the National Institute of Standards and Technology is smaller than a standard antenna with comparable properties. Its high efficiency is derived from the Z element inside the square that acts as a metamaterial, greatly… …   Wikipedia

  • Lakenheath-Bentwaters incident — The Lakenheath Bentwaters Incident was a series of radar and visual contacts with Unidentified Flying Objects that took place over airbases in eastern England on the night of 13 14 August 1956, involving both RAF and USAF personnel. The incident… …   Wikipedia

  • Radar météorologique — Un radar météorologique est un type de radar utilisé en météorologie pour repérer les précipitations, calculer leur déplacement et déterminer leur type (pluie, neige, grêle, etc.). La structure tridimensionnelle des données obtenues permet… …   Wikipédia en Français

  • Radar — For other uses, see Radar (disambiguation). A long range radar antenna, known as ALTAIR, used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on Kwajalein Atoll …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.