Editing Radome

{{Use American English|date = March 2019}}
{{Short description|Weatherproof structures enclosing antennea that emits radiation (Not Exclusively RADAR)}}
{{Use mdy dates|date = March 2019}}
[[File:Navy-Radome.jpg|right|260px|thumbnail|Geodesic radomes at the [[Misawa Air Base|Misawa Security Operations Center]], Misawa, Japan]]
[[File:HMS Daring SAMPSON is a multi-function AESA radar.jpg|thumb|Spherical radome mounted atop the mainmast of a [[Type 45 destroyer]]]]
[[File:E3D Sentry - RIAT 2009 (3871588664).jpg|thumb|A [[Boeing E-3 Sentry]], showing its rotodome mounted above the fuselage]]
{{wikt | radome}}

A '''radome''' (a [[portmanteau]] of "[[radar]]" and "[[dome]]") is a structural, weatherproof enclosure that protects a radar [[antenna (radio)|antenna]].<ref>{{cite book |title=A Dictionary of Aviation |first=David W. |last=Wragg |isbn=9780850451634 |edition=first |publisher=Osprey |date=1973 |page=220 }}</ref> The radome is constructed of material transparent to radio waves.  Radomes protect the antenna from weather and conceal antenna electronic equipment from view. They also protect nearby personnel from being accidentally struck by quickly rotating antennas.

Radomes can be constructed in several shapes{{snd}} spherical, [[geodesic dome|geodesic]], planar, etc.{{snd}} depending on the particular application, using various construction materials such as [[fiberglass]], [[polytetrafluoroethylene|polytetrafluoroethylene (PTFE)]]-coated fabric, and others.<ref name=":0">{{Cite journal |last=Latifiyan |first=Pouya |date=August 28, 2022 |title=What is Radome? |url=https://t.me/Qoqnoos_CATC/13 |journal=Qoqnoos Scientific Magazine |volume=1 |pages=13}}</ref>

In addition to radar protection, radomes on [[aircraft]] platforms also act as [[aircraft fairing|fairing]]s that streamline the antenna system, thus reducing [[drag (physics)|drag]]. When found on [[fixed-wing aircraft]] with forward-looking radar, as are commonly used for object or weather detection, the [[nose cone]]s often additionally serve as radomes. On [[airborne early warning and control]] (AEW&C) aircraft (e.g. the American [[E-3 Sentry]]), a [[discus]]-shaped rotating radome, often called a "'''rotodome'''", is mounted on the top of the [[fuselage]] for 360-degree scanning coverage. Some newer AEW&C configurations instead use three 120-degree [[phased array]] modules inside a stationary radome, examples being the Chinese [[KJ-2000]] and Indian [[DRDO AEW&CS|DRDO AEW&Cs]]. On fixed-wing and [[rotary-wing]] aircraft using [[microwave]] [[satellite]] for [[non-line-of-sight propagation|beyond-line-of-sight communication]], radomes often appear as bulged "blisters" on the fuselage.<ref>{{Cite web |url=http://www.jenoptik.com/en_30157_mrca_tornado_radome |title=example of helicopter radome |access-date=November 27, 2012 |archive-date=October 31, 2012 |archive-url=https://archive.today/20121031110723/http://www.jenoptik.com/en_30157_mrca_tornado_radome |url-status=dead }}</ref>

The use of radomes dates back as far as 1941.<ref>
{{cite book
 |last1                = Kozakoff
 |first1               = D. J.
 |year                 = 2010
 |title                = Analysis of Radome-enclosed Antennas
 |url                  = https://books.google.com/books?id=z9LtVCU2p8QC
 |series               = Artech House antennas and propagation library
 |edition              = 2
 |publication-place    = Norwood, Massachusetts
 |publisher            = Artech House
 |page                 = 3
 |isbn                 = 9781596934429
 |access-date          = 22 November 2024
 |quote                = In 1941, the first in-flight radome was a hemispherical nose radome fabricated from Plexiglas. It protected an experimental S-band, Western Electric radar flown in a B018A aircraft.
}} 
</ref>

The air supported radome built by Walter Bird in 1948 at the [[Calspan|Cornell Aeronautical Laboratory]] is the first pneumatic construction built in history.<ref>{{Cite journal |last=Collado Baíllo |first=Isabel |title=Walter Bird y las primeras construcciones neumáticas |url=http://www.reia.es/Numero20.html |journal=Revista Europea de Investigación en Arquitectura |volume=20 |pages=119–140}}</ref><ref name=":0" />

==Use==
[[File:H2S Radome And Scanner On Halifax.jpg|thumb|260px|right|One of the first radomes.  The radome (top) covers the [[H2S (radar)|H2S radar]] system rotating antenna (bottom) on a [[Handley Page Halifax|Halifax]] bomber]]

A radome is often used to prevent ice and [[freezing rain]] from accumulating on antennas. In the case of a spinning radar [[parabolic antenna]], the radome also protects the antenna from debris and rotational irregularities due to wind. Its shape is easily identified by its hardshell, which has strong properties against being damaged.

===Stationary antennas===
For stationary antennas, excessive amounts of ice can de-[[Tuner (radio)|tune]] the antenna to the point where its [[electrical impedance|impedance]] at the input [[frequency]] rises drastically, causing the [[standing wave ratio|voltage standing wave ratio]] (VSWR) to rise as well. This reflected power goes back to the [[transmitter]], where it can cause [[Thermal shock|overheating]]. A [[foldback (power supply design)|foldback]] [[electrical network|circuit]] can act to prevent this; however, one drawback of its use is that it causes the station's output power to drop dramatically, reducing its range.  A radome avoids that by covering the antenna's exposed parts with a sturdy, weatherproof material, typically fiberglass, keeping debris or ice away from the antenna, thus preventing any serious issues. One of the main driving forces behind the development of fiberglass as a structural material was the need during [[World War II]] for radomes.<ref>[[J.E. Gordon|Gordon, J.E.]], The New Science of Strong Materials: 2nd Edition, Pelican, 1976.</ref> When considering structural load, the use of a radome greatly reduces wind load in both normal and iced conditions. Many tower sites require or prefer the use of radomes for wind loading benefits and for protection from falling ice or debris.

Where radomes might be considered unsightly if near the ground, electric antenna heaters could be used instead. Usually running on [[direct current]], the heaters do not interfere physically or electrically with the [[alternating current]] of the radio [[transmission (telecommunications)|transmission]].

===Radar dishes===
For radar dishes, a single, large, ball-shaped dome also protects the rotational mechanism and the [[sensitivity (electronics)|sensitive]] [[electronics]], and is heated in colder climates to prevent icing.

The [[RAF Menwith Hill]] electronic surveillance base, which includes over 30 radomes, is widely believed to regularly intercept [[satellite]] communications. At Menwith Hill, the radome enclosures prevent observers from seeing the direction of the antennas, and therefore which satellites are being targeted. Similarly, radomes prevent observation of antennas used in [[ECHELON]] facilities.

The United States Air Force Aerospace Defense Command operated and maintained dozens of air defense radar stations in the contiguous United States and Alaska during the Cold War.  Most of the radars used at these ground stations were protected by rigid or inflatable radomes. The radomes were typically at least {{convert|50|ft|m|abbr=on|order=flip}} in diameter and the radomes were attached to standardized radar tower buildings that housed the radar transmitter, receiver and antenna.  Some of these radomes were very large.  The CW-620 was a space frame rigid radome with a maximum diameter of {{convert|150|ft|m|order=flip|abbr=on}}, and a height of {{convert|84|ft|m|order=flip|abbr=on}}.  This radome consisted of 590 panels, and was designed for winds up to {{convert|150|mph|km/h|order=flip|abbr=on}}. The total radome weight was {{convert|204,400|lb|kg|order=flip|abbr=on}} with a surface area of {{convert|39600|sqft|m2|order=flip|abbr=on}}.  The CW-620 radome was designed and constructed by Sperry-Rand Corporation for the Columbus Division of North American Aviation.  This radome was originally used for the FPS-35 search radar at Baker Air Force Station, Oregon. When Baker AFS was closed the radome was moved to provide a high-school gymnasium in Payette, Idaho. Pictures and documents are available online at [http://radomes.org/museum radomes.org/museum] for Baker AFS/821st Radar Squadron.

===Maritime satellites===
[[File:KNS radomes.jpg|thumb|260px|right|A yacht fitted with small KNS tracking dishes for [[SES Broadband for Maritime]], protected by radomes]] For [[Freight transport|maritime]] [[Communications satellite|satellite communications]] service, radomes are widely used to protect dish antennas which are continually tracking fixed satellites while the ship experiences pitch, roll and yaw movements. Large cruise ships and oil tankers may have radomes over 3{{nbs}}m in diameter covering antennas for broadband transmissions for television, voice, data, and the Internet, while recent developments allow similar services from smaller installations such as the 85&nbsp;cm motorised dish used in the [[SES Broadband for Maritime]] system. Small private yachts may use radomes as small as 26{{nbs}}cm in diameter for voice and low-speed data.

==Alternatives==
An [[active electronically scanned array]] radar has no moving antenna and so a radome is not necessary.<ref name=":0" /> An example of this is the pyramid which replaced the golfball-style radome installations at [[RAF Fylingdales]].

==Notes==
{{Reflist}}

==External links==
*[https://www.panoramio.com/photo/200293 Photograph of Mount Hebo while active] overlooking Pacific Ocean ''(link no longer works)''

{{commons category|Radomes}}

[[Category:Radar]]
[[Category:Domes]]
[[Category:Antennas (radio)]]
[[Category:British inventions]]