Airplane scattering (or most often reflection) refers to the reflection of a radio signal by the metal structure of a passing aircraft. It is observed on radio waves from
high frequency
High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) 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 ...
to VHF through to microwaves and, besides back-scattering, yields momentary propagation up to even in mountainous terrain. The most common back-scatter applications are
air-traffic radar,
bistatic forward-scatter guided-missile and airplane-detecting
trip-wire radar, and the US space radar.
It is also a less common propagation mode used by
radio amateurs
An amateur radio operator is someone who uses equipment at an amateur radio station to engage in two-way communication, two-way personal communications with other amateur operators on Frequency, radio frequencies Amateur radio frequency allocatio ...
.
History
Airplane scatter itself had been discovered in 1930, but radio amateur usage lagged until the late 80s. The advent of inexpensive
SDR based and
distributed real time flight tracking enabled precise scheduling, increasing feasibility.
Radio amateur usage
Compared to a single trail of
meteor scatter
Meteor burst communications (MBC), also referred to as meteor scatter communications, is a radio propagation mode that exploits the ionized trails of meteors during atmospheric entry to establish brief communications paths between radio stations ...
, the time of opening caused by a single airplane is longer it can be from 30 seconds up to a few minutes. Slight asymmetry can sometimes be encountered both in terms of exact timing and the gain of the path.
Range and possible contact lengths are affected by the size of the plane, flight level and the approximate crossing time of the central part of the straight line between the two communicating stations.
Both the onset and decay of the channel is rapid, so to improve success rate, a short contact procedure is used.
Contact opportunities can be predicted based on the precise flight paths of surrounding planes. There exists software for prediction using local (
Mode S The aviation transponder interrogation modes are the standard formats of pulsed sequences from an interrogating Secondary Surveillance Radar (SSR) or similar Automatic Dependent Surveillance-Broadcast (ADS-B) system. The reply format is usually refe ...
and
ADS-B) or online sources.
Microwave access using
high gain antenna
A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced interference from unwanted sources. Directional antennas provide increased performance ...
s needs to consider precise aiming that takes into account elevation angles as well.
See also
*
Meteor burst communications
Meteor burst communications (MBC), also referred to as meteor scatter communications, is a radio propagation mode that exploits the ionized trails of meteors during atmospheric entry to establish brief communications paths between radio stations ...
*
Tropospheric scatter
Tropospheric scatter, also known as troposcatter, is a method of communicating with microwave radio signals over considerable distances – often up to and further depending on frequency of operation, equipment type, terrain, and climate facto ...
References
External links
* http://www.qsl.net/g0isw/g0iswair.htm
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