The AMES Type 84, also known as the Microwave Early Warning or MEW, was a 23 cm wavelength
early warning radar
An early-warning radar is any radar system used primarily for the long-range detection of its targets, i.e., allowing defences to be alerted as ''early'' as possible before the intruder reaches its target, giving the air defences the maximum t ...
used by the
Royal Air Force
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
(RAF) as part of the
Linesman/Mediator
Linesman/Mediator was a dual-purpose civil and military radar network in the United Kingdom between the 1960s and 1984. The military side (Linesman) was replaced by the Improved United Kingdom Air Defence Ground Environment (IUKADGE), while the ...
radar network. Operating in the
L-band
The L band is the Institute of Electrical and Electronics Engineers (IEEE) designation for the range of frequencies in the radio spectrum from 1 to 2 gigahertz (GHz). This is at the top end of the ultra high frequency (UHF) band, at the lower en ...
gave it improved performance in rain and hail, where the primary
AMES Type 85
The AMES Type 85, also known by its rainbow code Blue Yeoman, was an extremely powerful early warning (EW) and fighter direction (GCI) radar used by the Royal Air Force (RAF) as part of the Linesman/Mediator radar network. First proposed in early ...
radar's performance dropped off. It operated beside the Type 85 and
RX12874
RX12874, also known as the Passive Detection System (PDS) and by its nickname "Winkle", was a radar detector system used as part of the Royal Air Force's Linesman/Mediator radar network until the early 1980s. Winkle passed out of service along wi ...
in Linesman, and moved to the
UKADGE
The Improved United Kingdom Air Defence Ground Environment, normally shortened to either UKADGE or IUKADGE, was the Royal Air Force's (RAF) ground-controlled interception system covering the British Isles during the 1990s. It consisted of a number ...
system in the 1980s before being replaced during UKADGE upgrades in the early 1990s.
The Type 84 had a decade-long development period that saw the system being repeatedly redesigned. It was first conceived in 1951 during the
ROTOR
Rotor may refer to:
Science and technology
Engineering
*Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element so called the stator
* Helicopter rotor, the rotary wing(s) of a rotorcraft ...
program as a
megawatt
The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units, International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), ...
-powered
S-band
The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional ...
system that would replace the WWII-era
Chain Home
Chain Home, or CH for short, was the codename for the ring of coastal Early Warning radar stations built by the Royal Air Force (RAF) before and during the Second World War to detect and track aircraft. Initially known as RDF, and given the off ...
radars for early warning. But an experimental system developed at the
Royal Radar Establishment
The Royal Radar Establishment was a research centre in Malvern, Worcestershire in the United Kingdom. It was formed in 1953 as the Radar Research Establishment by the merger of the Air Ministry's Telecommunications Research Establishment (TRE) a ...
(RRE) offered similar performance and would be available long before the MEW's 1957 target date. Put into operation as the
AMES Type 80
The AMES Type 80, sometimes known by its development rainbow code Green Garlic, was a powerful early warning (EW) and ground-controlled interception (GCI) radar developed by the Telecommunications Research Establishment (TRE) and built by Decca f ...
in 1953, the immediate need for MEW was eliminated. MEW was then assigned a lower priority and handed off to
Marconi for further development.
A new concept emerged as an L-band counterpart to the Type 80, adding an advanced
moving target indication
Moving target indication (MTI) is a mode of operation of a radar to discriminate a target against the clutter. It describes a variety of techniques used for finding moving objects, like an aircraft, and filter out unmoving ones, like hills or trees ...
(MTI) system. In this form, the system was ordered into production as the Type 84 in July 1957. That same month, concerns about the new
carcinotron
A backward wave oscillator (BWO), also called carcinotron or backward wave tube, is a vacuum tube that is used to generate microwaves up to the terahertz range. Belonging to the traveling-wave tube family, it is an oscillator with a wide elect ...
jammer grew. MEW was repositioned as an anti-jamming radar using a powerful 10 MW
klystron
A klystron is a specialized linear-beam vacuum tube, invented in 1937 by American electrical engineers Russell and Sigurd Varian,Pond, Norman H. "The Tube Guys". Russ Cochran, 2008 p.31-40 which is used as an amplifier for high radio frequenci ...
, but this system failed to work. A 5 MW wide-band
magnetron
The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while ...
replaced the klystron, but this required a new MTI and antenna system as well. By the time these were ready the magnetron was not, and it finally settled on a 2.5 MW version, compromising its capability as an anti-jamming system.
During development, MEW was the primary radar of the Stage 2 ROTOR plans and was intended to hand-off targets to the
Blue Envoy
Blue Envoy (a Rainbow Code name) was a British project to develop a ramjet-powered surface-to-air missile. It was tasked with countering supersonic bomber aircraft launching stand-off missiles, and thus had to have very long range and high-speed ...
long-range missile. But the RRE once again trumped the Type 84 with their new
Blue Yeoman
The AMES Type 85, also known by its rainbow code Blue Yeoman, was an extremely powerful early warning (EW) and fighter direction (GCI) radar used by the Royal Air Force (RAF) as part of the Linesman/Mediator radar network. First proposed in early ...
design, which was much more powerful and offered
frequency agility Frequency agility is the ability of a radar system to quickly shift its operating frequency to account for atmospheric effects, jamming, mutual interference with friendly sources, or to make it more difficult to locate the radar broadcaster through ...
. Deployment of Type 84 went ahead anyway, largely because it was complete and offered a number of complimentary features. The first operational Type 84 was handed over to the RAF at
RAF Bawdsey
Royal Air Force Bawdsey or more simply RAF Bawdsey is a former Royal Air Force station situated on the eastern coast in Suffolk, England. Also known as Bawdsey Research Station (BRS), the first Chain Home radar station was built there, characte ...
in October 1962. Three additional units came online during the 1960s, and the fifth from the original order was instead sent to
Cyprus
Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is geo ...
and placed on
Mount Olympus
Mount Olympus (; el, Όλυμπος, Ólympos, also , ) is the highest mountain in Greece. It is part of the Olympus massif near the Thermaic Gulf of the Aegean Sea, located in the Olympus Range on the border between Thessaly and Macedonia, be ...
. The last unit shut down in 1994.
History
Origins in ROTOR
In the early 1950s the threat of nuclear attack by the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
led the UK to design an extensive radar network known as
ROTOR
Rotor may refer to:
Science and technology
Engineering
*Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element so called the stator
* Helicopter rotor, the rotary wing(s) of a rotorcraft ...
. ROTOR initially envisioned two stages, the first using upgraded
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
radars like
Chain Home
Chain Home, or CH for short, was the codename for the ring of coastal Early Warning radar stations built by the Royal Air Force (RAF) before and during the Second World War to detect and track aircraft. Initially known as RDF, and given the off ...
, and then, from 1957, these would be replaced by a dramatically more powerful radar known as the Microwave Early Warning set, or MEW. The goal for the MEW was to detect a bomber at .
In 1951 the
Telecommunications Research Establishment
The Telecommunications Research Establishment (TRE) was the main United Kingdom research and development organization for radio navigation, radar, infra-red detection for heat seeking missiles, and related work for the Royal Air Force (RAF) d ...
(TRE) began experimenting with new low-noise
crystal detector
A crystal detector is an obsolete electronic component used in some early 20th century radio receivers that consists of a piece of crystalline mineral which rectifies the alternating current radio signal. It was employed as a detector (demod ...
s that improved reception by 10 dB, and new
cavity magnetron
The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while ...
s of roughly 1 MW power. Combining these together on a lashed-up antenna system from the war-era
AMES Type 14
Ames may refer to:
Places United States
* Ames, Arkansas, a place in Arkansas
* Ames, Colorado
* Ames, Illinois
* Ames, Indiana
* Ames, Iowa, the most populous city bearing this name
* Ames, Kansas
* Ames, Nebraska
* Ames, New York
* Ames, Oklah ...
, produced a test unit known as "Green Garlic". Although somewhat shorter-ranged than MEW, all that was required to complete development was a new antenna and its physical mounting system. It filled most of the MEW requirements but would be available years earlier.
New concept
As these
AMES Type 80
The AMES Type 80, sometimes known by its development rainbow code Green Garlic, was a powerful early warning (EW) and ground-controlled interception (GCI) radar developed by the Telecommunications Research Establishment (TRE) and built by Decca f ...
s went into service, there was some debate what to do with the MEW. During this period the TRE had also been experimenting with
moving target indication
Moving target indication (MTI) is a mode of operation of a radar to discriminate a target against the clutter. It describes a variety of techniques used for finding moving objects, like an aircraft, and filter out unmoving ones, like hills or trees ...
(MTI) systems on an
AMES Type 11 radar. These systems removed non-moving returns from the
radar display
A radar display is an electronic device to present radar data to the operator. The radar system transmits pulses or continuous waves of electromagnetic radiation, a small portion of which backscatter off targets (intended or otherwise) and retur ...
, which is extremely useful for eliminating reflections off of local terrain which otherwise leaves large areas on the display where aircraft cannot be seen. This led to the idea that MEW would be an L-band counterpart to Type 80 with a good MTI system. MEW development was spun off to
Marconi Wireless
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimental technologies for tr ...
.
An additional desire was to have the system provide
height finding as well, which would eliminate the separate radars that would be needed for that role. As early as 1954, Marconi had demonstrated that the height finding function in the L-band was impractical. A new specification emerged returning MEW to a MTI-equipped Type 80, using the same antenna system.
MTI development
MTI is accomplished by comparing an incoming signal from the current radar pulse with the last one sent, and looking for changes in frequency due to the
Doppler shift
The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who d ...
. This requires the last pulse to be stored so it can be compared with the current one, which is difficult to do at microwave frequencies. The simplest solution is to use a much lower
intermediate frequency
In communications and electronic engineering, an intermediate frequency (IF) is a frequency to which a carrier wave is shifted as an intermediate step in transmission or reception. The intermediate frequency is created by mixing the carrier sign ...
(IF) as the basis for the pulse and then electronically multiply its frequency before sending, dividing it again on reception for storage. This requires the IF to be extremely stable, which makes it difficult to accomplish with a
magnetron
The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while ...
as these devices output a slightly different signal, in both frequency and phase, with every pulse. To make this work, the MEW had to use a
klystron
A klystron is a specialized linear-beam vacuum tube, invented in 1937 by American electrical engineers Russell and Sigurd Varian,Pond, Norman H. "The Tube Guys". Russ Cochran, 2008 p.31-40 which is used as an amplifier for high radio frequenci ...
, and based on the goal of outperforming the Type 80, the new MEW plans called for a 10 MW klystron.
Development took place at Marconi's radar center on
Bushy Hill, northeast of London. The MTI system progressed well, delivering a system that not only eliminated any non-moving objects, but also had a feature that could be controlled to offset movement due to wind, which was particularly useful for eliminating the images of heavy rain or the use of
chaff
Chaff (; ) is the dry, scaly protective casing of the seeds of cereal grains or similar fine, dry, scaly plant material (such as scaly parts of flowers or finely chopped straw). Chaff is indigestible by humans, but livestock can eat it. In agri ...
. The system allowed the operator to select three rectangular areas on the screen and dial in a windspeed and direction for each one.
Unfortunately, development of the high-power klystron did not progress nearly as well. By 1957 the best example available had demonstrated 10 MW when sent into a dummy load, but when attached to a Type 80 antenna this dropped to a maximum of only 7 MW, and that was only on occasion. The problem was due to significant losses in the
waveguide
A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities de ...
. Extensive efforts were made to improve both the klystron and the waveguide, but in 1958 the decision was made to abandon the klystron.
In place of the klystron, Marconi suggested using an existing magnetron that had proven itself in operation on their test rig at Bushy Hill in use since 1956. This system had been used during air exercises in 1956's Operation Stronghold, where it demonstrated its ability to track in rain, but did have problems with the display of "
angels
In various theistic religious traditions an angel is a supernatural spiritual being who serves God.
Abrahamic religions often depict angels as benevolent celestial intermediaries between God (or Heaven) and humanity. Other roles include ...
". The magnetron produced only 2 MW, significantly less than desired, but there did appear to be some development potential. To make MTI work with a magnetron, which does not use an intermediate frequency and is not stable, an emerging technique known as
COHO
The coho salmon (''Oncorhynchus kisutch;'' Karuk: achvuun) is a species of anadromous fish in the salmon family and one of the five Pacific salmon species. Coho salmon are also known as silver salmon or "silvers". The scientific species name is ...
was applied. This taps off a small amount of signal from the magnetron as it sends the pulse and uses that as its reference instead of an external IF.
In July 1957, the Air Staff placed an order for four MEWs, which were given the official Type 84 name at that point. Three of these were to be used within a reduced Type 80 network, and another was for use at
RAF Akrotiri
RAF Akrotiri ( el, Βασιλική Πολεμική Αεροπορία Ακρωτηρίου) is a large Royal Air Force base on the Mediterranean island of Cyprus. It is located in the Western Sovereign Base Area, one of two areas which compr ...
on
Cyprus
Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is geo ...
.
Carcinotron
![Carcinotron jamming a pulse radar unit](https://upload.wikimedia.org/wikipedia/commons/7/7e/Carcinotron_jamming_a_pulse_radar_unit.png)
In 1950, engineers at the French company
CSF (now part of
Thales Group
Thales Group () is a French multinational company that designs, develops and manufactures electrical systems as well as devices and equipment for the aerospace, defence, transportation and security sectors. The company is headquartered in Paris' ...
) introduced the
carcinotron
A backward wave oscillator (BWO), also called carcinotron or backward wave tube, is a vacuum tube that is used to generate microwaves up to the terahertz range. Belonging to the traveling-wave tube family, it is an oscillator with a wide elect ...
, a
microwave
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...
-producing
vacuum tube
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied.
The type kn ...
that could be rapidly tuned across a wide range of frequencies by changing the input voltage. By continually sweeping through the frequencies of known
radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
s, it would overpower the radar's own reflections, and blind them. Its extremely wide
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
meant that a single carcinotron could be used to send
jamming signals against any radar it was likely to meet, and the rapid tuning meant it could do so against multiple radars at the same time, or rapidly sweep through all potential frequencies to produce
barrage jamming
Barrage jamming is an electronic warfare technique that attempts to blind ("jam") radar systems by filling the display with noise, rendering the broadcaster's ''blip'' invisible on the display, and often those in the nearby area as well. "Barrage ...
.
The carcinotron was revealed publicly in November 1953. The
Admiralty Signals and Radar Establishment
The Admiralty Signal and Radar Establishment (ASRE) originally known as the Experimental Department and later known as the Admiralty Signal Establishment (ASE) was a research organisation of the British Royal Navy established in 1917. It existed ...
purchased one and fit it to a
Handley Page Hastings
The Handley Page HP.67 Hastings is a retired British troop-carrier and freight transport aircraft designed and manufactured by aviation company Handley Page for the Royal Air Force (RAF). Upon its introduction to service during September 1948, ...
named ''Catherine'', testing it against the latest Type 80 late that year. As they feared, it rendered the radar display completely unreadable, filled with noise that hid any real targets. Useful jamming was accomplished even when the aircraft was under the
radar horizon
The radar horizon is a critical area of performance for aircraft detection systems that is defined by the distance at which the radar beam rises enough above the Earth's surface to make detection of a target at low level impossible. It is associ ...
, in which case other aircraft had to be to the sides before they were visible outside the jamming signal. The jammer was so effective that it appeared to render long-range radar useless.
These developments were not made known to the Air Staff until July 1957, and it immediately threw their entire "1958 Plan" into disarray. They arranged their own tests and found that the RRE's previous tests against the Type 80 and
AMES Type 82
The AMES Type 82, also widely known by its rainbow codename Orange Yeoman, was an S-band 3D radar built by Marconi and used by the Royal Air Force (RAF), initially for tactical control and later for air traffic control (ATC).
Development sta ...
were precisely as bad as the RRE indicated. The L-band Type 84 was even more easily jammed then the S-band Type 80, which was itself considered useless in the face of this threat. Lacking any solution, no further work on the Plan was carried out, with no meetings by the planning committee at all between December 1957 and December 1958.
Plan Ahead
The RRE had been investigating the problems due to jamming starting in 1955 and presented their first concept the next year. This demanded an extremely high-power radar sent out of a huge
parabolic antenna
A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or pa ...
. The idea was to focus as much energy as possible on the target so the radar signal would simply overwhelm any practical jammer, while at the same time reducing
side lobe
In antenna engineering, sidelobes are the lobes (local maxima) of the far field radiation pattern of an antenna or other radiation source, that are not the ''main lobe''.
The radiation pattern of most antennas shows a pattern of "''lobes'' ...
s as much as possible to eliminate spurious signals from the jammer reaching the receiver.
Known as Blue Riband, the system required four antennas arranged in a square running on a turntable built on top of a modified railroad bed. This system would have made it among the most powerful radars ever built, and a convincing answer to the carcinotron problem. Additionally, the massive power output gave it formidable range, meaning a reduced network of stations could provide the same coverage as the dozens of Type 80's in service, which would reduce manpower requirements. In 1958, a new network emerged with five Blue Riband stations with a few additional Type 80s and Type 84s kept on the flanks for additional coverage.
This new plan ran directly into the
1957 Defence White Paper
The 1957 White Paper on Defence (Cmnd. 124) was a British white paper issued in March 1957 setting forth the perceived future of the British military. It had profound effects on all aspects of the defence industry but probably the most affected wa ...
. This paper noted the emergence of the guided missile would have two significant effects on the strategic outlook. One was that attacks by enemy bombers could be fended off by
surface-to-air missile
A surface-to-air missile (SAM), also known as a ground-to-air missile (GTAM) or surface-to-air guided weapon (SAGW), is a missile designed to be launched from the ground to destroy aircraft or other missiles. It is one type of anti-aircraft syst ...
s, which had already been earmarked as the primary anti-aircraft weapon of the future in the form of
Blue Envoy
Blue Envoy (a Rainbow Code name) was a British project to develop a ramjet-powered surface-to-air missile. It was tasked with countering supersonic bomber aircraft launching stand-off missiles, and thus had to have very long range and high-speed ...
. The other was that the emergence of the
medium range ballistic missile
A medium-range ballistic missile (MRBM) is a type of ballistic missile with medium range, this last classification depending on the standards of certain organizations. Within the U.S. Department of Defense, a medium-range missile is defined by ...
would replace those bombers in the strategic role as early as 1965, at which point any air defense, including Blue Envoy, was useless.
Examining these concerns, the Air Ministry returned a further reduced system known as Plan Ahead. This used only three primary radars based on greatly reduced versions of the Blue Riband known as Blue Yeoman, and a much smaller flanking network. Data from all of these radars would be sent to a centralized control center where a single view of the airspace would be constructed. In this system, the purpose of Type 84 was somewhat diluted, with its main advantage being that the MTI system would allow it to examine areas close to the radar, where the Type 85 would be blinded by local returns. This would have the advantage of allowing it to track interceptors taking off from nearby airfields.
The use of missiles in the strategic role, and how rapidly they would arrive, produced a furious debate through the Air Ministry and Whitehall. Matters finally came to a head in 1959, when Prime Minister
Harold Macmillan
Maurice Harold Macmillan, 1st Earl of Stockton, (10 February 1894 – 29 December 1986) was a British Conservative statesman and politician who was Prime Minister of the United Kingdom from 1957 to 1963. Caricatured as "Supermac", he ...
delivered an either-or choice; if the Air Ministry remained adamant in deploying Plan Ahead, they could but only at the price of ending all other air-defense projects. Blue Envoy, the
Operational Requirement F.155
Operational Requirement F.155 was a specification issued by the British Ministry of Supply on 15 January 1955 for an interceptor aircraft to defend the United Kingdom from Soviet high-flying nuclear-armed supersonic bombers.
Discussion about th ...
interceptor,
Blue Joker
Blue Joker was an experimental moored balloon-mounted, airborne early-warning radar project developed by the Royal Radar Establishment (RRE) starting in 1953. The idea was to position the radar high in the air in order to extend its radar horizon ...
radar and many other projects were cancelled.
Further changes
During the second half of 1958, the Type 84's role in the new network was examined, leading to yet another series of significant changes.
The basic idea behind Blue Yeoman was to spread the selection of frequencies used by the radar in order to force the jammer to spread out its signal as well. Calculations showed that a carcinotron might be able to produce 10 W of signal at any one frequency if it was forced to broadcast over a
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
about of the radar's operational frequency. For the S-band Blue Yeoman's base frequency of 3,000 MHz, that meant it had to use a bandwidth of about 500 MHz in order to force the jammer to dilute its signal below what the radar's own return might produce.
In contrast, the L-band Type 84's base frequency was 1,200 MHz, so to produce the same spread, it needed to cover about 150 MHz. Normally a magnetron uses a single base frequency, but some "wobble" is evident. But Blue Yeoman also relied on very high power levels; it was only high power in combination with bandwidth that made the system effective. Accordingly, a new 5 MW magnetron was ordered. There was some hope that enemy jammers might not operate against the L-band at all.
The Type 80 antenna being used for the Type 84 had a mesh surface that was tuned to the frequency of the radar and had an effective bandwidth of about 50 MHz, so a new antenna would be needed. The decision was made to use the antenna being developed for the Blue Yeoman, a solid-surface design with no effective bandwidth limitation. With the Type 85, the signal was being fed from a dozen klystrons spread out vertically along the face of the reflector, so to get this to work with the single magnetron in the Type 84, a system of splitters was added to separate the single signal into eight separate
feed horn
A feed horn (or feedhorn) is a small horn antenna used to couple a waveguide to e.g. a parabolic dish antenna or offset dish antenna for reception or transmission of microwave. A typical application is the use for satellite television recept ...
s. The original turning gear from the Type 80 would be retained.
During 1959,
wind tunnel
Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...
tests on the new antenna design running on Type 80 turning gear showed that when the antenna was perpendicular to the wind, the
lift
Lift or LIFT may refer to:
Physical devices
* Elevator, or lift, a device used for raising and lowering people or goods
** Paternoster lift, a type of lift using a continuous chain of cars which do not stop
** Patient lift, or Hoyer lift, mobile ...
created by its curved rear surface caused it to pull itself off the mount. The simplest solution was to mount a second "dish" on the back of the first, thereby evening out the lift forces. After some consideration, it was decided that this second dish would be used as an
IFF Mark X IFF Mark X was the NATO standard military identification friend or foe transponder system from the early 1950s until it was slowly replaced by the IFF Mark XII in the 1970s. It was also adopted by ICAO, with some modifications, as the civilian ai ...
receiver, which also operated in the L-band. This would allow a single unit to produce maps of target echos as well as highly accurate positions of the friendly interceptors. Ultimately, this system was never used; there was doubt that enough interrogation pulses would be received in the very narrow beam to be useful. In production systems, a conventional IFF antenna was placed on top of the antenna, facing the same direction as the Type 84.
Deployment
In 1960 it was clear that getting funding for Plan Ahead was going to be difficult, and that even if it was funded, the initial system would be all that would ever be built. Given this, the base arrangement was changed to move the inland site to the coast at
RAF Bramcote
Royal Air Force Bramcote or more simply RAF Bramcote is a former Royal Air Force station located south-east of Nuneaton, Warwickshire, England used during the Second World War. It later became HMS Gamecock and then Gamecock Barracks.
Royal Air ...
, which would reduce the coverage over the Midlands, but improve the system's early warning capabilities over the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
. Three of the Type 84s would be placed at the main Plan Ahead bases, Bramcote,
RAF Staxton Wold
Remote Radar Head Staxton Wold or RRH Staxton Wold is an air defence radar station operated by the Royal Air Force, located near Scarborough in North Yorkshire, England. As it has been a radar site continuously since 1939, it has a claim to be t ...
and
RAF Neatishead
Remote Radar Head Neatishead ( ) or RRH Neatishead is an air defence radar station operated by the Royal Air Force. It is located approximately north east of Norwich in Norfolk, England.
It was established during the Second World War and consi ...
, while two additional Type 84s would be installed at
RAF Saxa Vord
Remote Radar Head Saxa Vord or RRH Saxa Vord (aka RAF Saxa Vord), is a Royal Air Force radar station located on the island of Unst, the most northern of the Shetland Islands in Scotland. As of July 2019 it is once more a fully operational radar ...
and
RAF Buchan
Royal Air Force Buchan or more simply RAF Buchan is a former Royal Air Force station near Peterhead in Aberdeenshire, Scotland.
Buchan opened in 1952 as a radar centre in the ROTOR radar network. It was soon upgraded with the installation of th ...
. The Type 84 at Saxa Vord was later dropped, while the test installation at Bawdsey was earmarked for
RAF Bishops Court
Royal Air Force Bishopscourt or more simply RAF Bishopscourt is a former Royal Air Force airfield, radar control and reporting station located on the south east coast of Northern Ireland, approximately from Downpatrick, County Down, Northern Ir ...
in
Northern Ireland
Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...
, closing the "back door" approach, and the Buchan example moved to Cyprus.
Even this limited version of the network was subject to continual agitation from the cabinet, and in 1962 the Air Ministry asked for yet another study on the layout, wondering if the Type 85s might be abandoned in favour of a system with only three stations in total, all using Type 84. At a meeting in March 1962, it was decided that it was all or nothing - the smaller or simplified deployments were simply not worth building at all. Concurrently, other groups were studying whether the military early warning and tracking needs could be combined with civilian
air traffic control
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airs ...
systems. Several reports all suggested this was both possible and highly desirable, and Plan Ahead became
Linesman/Mediator
Linesman/Mediator was a dual-purpose civil and military radar network in the United Kingdom between the 1960s and 1984. The military side (Linesman) was replaced by the Improved United Kingdom Air Defence Ground Environment (IUKADGE), while the ...
. The system was given the final go-ahead on 24 October 1962.
Meanwhile, the new 5 MW magnetron had failed to mature, and the system went into production with a slightly upgraded version of the original 2 MW, operating at 2.5 MW. In this form, the final Type 84 emerged after a decade of changes. Plans called for the first system to be installed at
RAF Bawdsey
Royal Air Force Bawdsey or more simply RAF Bawdsey is a former Royal Air Force station situated on the eastern coast in Suffolk, England. Also known as Bawdsey Research Station (BRS), the first Chain Home radar station was built there, characte ...
in early 1960 and handed over operationally in 1961. This was ultimately late; the system was handed over on 2 October 1962. This demonstrated problems against an
English Electric Canberra
The English Electric Canberra is a British first-generation, jet-powered medium bomber. It was developed by English Electric during the mid- to late 1940s in response to a 1944 Air Ministry requirement for a successor to the wartime de Havil ...
when flying at low altitudes directly at the station, although this had been expected. This led to calls for improved low-level performance, which was delivered by redesigning the feed network for the second Type 84 that was being installed at Neatishead, which entered service in October 1963. The remaining two units followed over the next few months.
It had been planned that the Bawdsey install would move to Bishops Court after the nearby Neatishead installation was complete, initially expected to move in early 1965. Although the program was somewhat delayed, preparations for the move were being made when, on 16 February 1966, LAC Cheeseman started a fire that burned out the entire bunker complex and resulted in the deaths of three local firemen who had been called in an attempt to get the fire under control. The Type 84 finally moved in 1970, completing testing in 1972. The Type 80 serving this location, at nearby Killard Point, was kept operational as well.
The Type 84 entered service only slightly delayed, and the Type 85 was completed by 1968, both of which were considered a success. The same was not true for the data handling portion of the Linesman system, which faced repeated delays and only entered minimal operation on 18 December 1973. It was officially handed over to Strike Command on 1 February 1974 and declared in-service on 31 March. By that time it was already considered obsolete; some of the smaller supplier companies were no longer in the computer business and the germanium
transistor
upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink).
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch e ...
s used in the Plessy computers were no longer produced. Even its programmers suggested none of it actually worked, and the RAF itself finally reported that it was "so obsolete, it could not cope with any air threat."
UKADGE
When Linesman was first being considered the belief was that any war in Europe would be nuclear, and that any air attack on England would be as well. In this environment, there was no point trying to harden command centres, they would be destroyed if attacked. This led to the main control center, L1, being moved to an aboveground office building near
Heathrow Airport
Heathrow Airport (), called ''London Airport'' until 1966 and now known as London Heathrow , is a major international airport in London, England. It is the largest of the six international airports in the London airport system (the others be ...
. Fighter Command repeatedly protested, noting that the entire air defence network might be taken out by an explosive truck on the road outside the building or jamming of the microwave links that fed it. They repeatedly called for command to be devolved to the radar stations, as it had been in the Type 80 era.
Moreover, the strategic situation changed once again. As the Soviets gained strategic parity with the US, the idea of meeting any Warsaw Pact offence with tactical nuclear weapons was no longer seen as a safe response as the US was now just as deterred from using their strategic forces as the Soviets had been formerly. Additionally, new weapons like the
TOW missile
The BGM-71 TOW ("Tube-launched, Optically tracked, Wire-guided") is an American anti-tank missile. TOW replaced much smaller missiles like the SS.10 and ENTAC, offering roughly twice the effective range, a more powerful warhead, and a greatly ...
fired from
attack helicopter
An attack helicopter is an armed helicopter with the primary role of an attack aircraft, with the offensive capability of engaging ground targets such as enemy infantry, military vehicles and fortifications. Due to their heavy armament they ...
s appeared to offer an all-conventional method of defeating the Pact. Now it appeared war in Europe would have a long conventional phase, and air attack on England was likely yet unlikely to be nuclear. This was especially true in light of newer long-range Soviet aircraft that could approach the UK at low level and thereby avoid detection altogether.
Studies of a replacement system started in 1972, and multiple reports were produced on the topic over the next year. They proposed using modern commercial computers in place of the specialized systems of Linesman, adding complete digitization of all signals from all radars in the network, upgrading links to their counterparts in
NADGE
The NATO Integrated Air Defense System (short: NATINADS) is a command and control network combining radars and other facilities spread throughout the NATO alliance's air defence forces. It formed in the mid-1950s and became operational in 1962 as ...
, which were at that time forwarded over voice lines, and devolving command to new hardened CRC centers, remote from the radar sites. L1 would remain in use, but primarily to disseminate information outside of Strike Command and to build the nationwide
Recognized Air Picture. The original radar systems of Linesman would remain in the new network, but would be supplanted by low-level coverage provided by decades-old
Avro Shackleton
The Avro Shackleton is a British long-range maritime patrol aircraft (MPA) which was used by the Royal Air Force (RAF) and the South African Air Force (SAAF). It was developed by Avro from the Avro Lincoln bomber, which itself had been a devel ...
aircraft fit with new radars, pending their replacement by similar conversions of the
Hawker Siddeley Nimrod
The Hawker Siddeley Nimrod is a retired maritime patrol aircraft developed and operated by the United Kingdom. It was an extensive modification of the de Havilland Comet, the world's first operational jet airliner. It was originally designed ...
. The
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
could also feed in information from their ships.
As had occurred with Linesman, UKADGE soon ran into huge delays on the software side, and was itself delayed well into the 1980s. In spite of glowing reviews by its creators, the system was an utter failure from the start. The Nimrod displayed this in excellent fashion when it was first demonstrating its ability to track unknown aircraft over England but instead demonstrated it was incapable of distinguishing aircraft from cars on the
motorway
A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms i ...
below. The project was eventually cancelled in 1986 in favour of buying several American
AWACS aircraft.
Decommissioning
UKADGE found itself in the same situation as Linesman before it; the lengthy delays, cost overruns and obsolescence led to calls for its replacement before it was operational. This led to the
Improved UKADGE or IUKADGE, which further upgraded the computer systems, communications systems, and eventually the radars themselves. While UKADGE had devolved the command systems to survivable sites, the radars themselves were sited close to shore and easy to destroy. A major goal of IUKADGE was to replace the Linesman radars with mobile units that could be stored off-site in secure locations and then brought online quickly after an attack.
Existing sources do not record when the last Type 84 stood down, but it was likely along with the rest of the Linesman sites in 1996.
Notes
References
Citations
Bibliography
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* {{cite journal
, title=UKADGE: Transatlantic Collaboration in Defence Technology
, first=Michael , last=Witt
, doi=10.1080/03071848308523513
, journal=The RUSI Journal
, volume=128 , issue=3
, date=1983
, pages=3, 54–57
Military radars of the United Kingdom
Ground radars
Military equipment introduced in the 1960s