backscatter

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Related to backscatters: backscatter radiation

backscatter

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Backscatter allows communication within the skip zone. Normally, station within skip zone cannot hear transmitting station. In this case Y cannot hear station X. Station, however, Z can hear station X by normal ionospheric propagation. On the other hand, when backscatter is strong enough station Y can hear station X, even though Y is within the skip zone.
i. A form of ionospheric propagation of electromagnetic waves via the E and F layers. These layers are highly ionized and have properties of reflecting electromagnetic waves back to the earth. Normally, almost all electromagnetic signals are returned to the earth at roughly equivalent angles of incidence. However, some amount of electromagnetic energy is scattered in all directions. Some energy may be reflected back toward the transmitting station into the skip zone. A receiving station within this skip zone is thus able to receive the transmission. Also called echo.
ii. In radar, the portion of the microwave energy scattered by the terrain surface directly back toward the antenna.
References in periodicals archive ?
Some of the last backscatter machines were removed from Manchester Airport just last month.
TSA rolled out the backscatter machines in October 2010 and subsequently authorized enhanced patdowns -- which could include the touching of breasts, buttocks and genitals -- for passengers unwilling to submit to those scanners.
Beta electrons that scatter from any material before hitting the detector will lose energy, leading to the same problem as detector backscatter.