{{Short description|Radio frequency propagation}} {{Use American English|date=May 2021}} {{Use mdy dates|date=May 2021}} thumb | right '''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 to VHF through to microwaves<ref>{{cite web|url=https://w3sz.com/AircraftScatteron10and24GHzMUDv5a.pdf|access-date=22 April 2023|website=w3sz.com|title=Aircraft Scatter on 10 and 24 GHz using JT65c and ISCAT-A}}</ref> and, besides back-scattering, yields momentary propagation up to {{convert|800|km|sp=us|abbr=off}} 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.
== History == Airplane scatter itself had been discovered in 1930, but radio amateur usage lagged until the late 1980s. The advent of inexpensive SDR based and distributed real time flight tracking enabled precise scheduling, increasing feasibility.<ref>{{cite web|url=https://w3sz.com/W3SZ-NEW-AirCraftScatterNEWS2014.pdf|access-date=22 April 2023|date=12 April 2014|author=Roger Rehr|website=w3sz.com|title=Aircraft Scatter for the Microwave Enthusiast}}</ref><ref>{{cite web|url=http://www.vk3hz.net/ae.htm|title=Aircraft Enhancement Articles|website=www.vk3hz.net}}</ref>
== Radio amateur usage ==
Compared to a single trail of meteor scatter, the time of opening caused by a single airplane is longer{{Snd}} 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.<ref>{{cite web|url=http://home.swipnet.se/2ingandlin/ACS.htm|title=AIRCRAFT SCATTER|first=INGOLF|last=LARSSON|website=home.swipnet.se|access-date=2017-06-11|archive-url=https://web.archive.org/web/20170914091357/http://home.swipnet.se/2ingandlin/ACS.htm|archive-date=2017-09-14|url-status=dead}}</ref>
Both the onset and decay of the channel is rapid, so to improve success rate, a short contact procedure is used.<ref>{{cite web|url=http://www.dj5ar.de/?page_id=998|title=Aircraft Scatter|date=22 July 2013|publisher=}}</ref>
Contact opportunities can be predicted based on the precise flight paths of surrounding planes. There exists software for prediction using local (Mode S and ADS-B) or online sources.<ref>{{cite web|url=http://sk0ct.se/propagation/flygscatter1.htm|title=SBS-1 a new tool|website=sk0ct.se}}</ref><ref>{{cite web |title=W3SZ Aircraft Scatter Page |url=http://www.nitehawk.com/w3sz/AircraftScatter.htm |url-status=dead |archive-url=https://web.archive.org/web/20250120230301/https://w3sz.com/AircraftScatter.htm |archive-date=January 20, 2025 |website=www.nitehawk.com}}</ref>
Microwave access using high gain antennas needs to consider precise aiming that takes into account elevation angles as well.<ref>{{cite web|url=http://zl4plm.com/index.php/2016/06/12/aircraft-scatter-elevation-angles/|title=Home of ZL4PLM and ZL4EME{{Snd}} Aircraft Scatter Elevation Angles|website=zl4plm.com}}</ref>
== See also == * Meteor burst communications * Tropospheric scatter
== References == {{Reflist|30em}}
== External links == * http://www.qsl.net/g0isw/g0iswair.htm
{{RF Propagation Navbox}}
Category:Radio frequency propagation