Anthorn Radio Station is a naval and government radio transmitting station located near

Anthorn Anthorn (pronounced ) is a village in Cumbria, England. Historic counties of England, Historically in Cumberland, it is situated on the south side of the Solway Firth, on the River Wampool, Wampool estuary, about west of Carlisle, Cumbria, C ...

Cumbria Cumbria ( ) is a ceremonial and non-metropolitan county in North West England, bordering Scotland. The county and Cumbria County Council, its local government, came into existence in 1974 after the passage of the Local Government Act 1972. Cumb ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

, overlooking the

Solway Firth The Solway Firth ( gd, Tràchd Romhra) is a firth that forms part of the border between England and Scotland, between Cumbria (including the Solway Plain) and Dumfries and Galloway. It stretches from St Bees Head, just south of Whitehaven in ...

, and is operated by

Babcock International Babcock International Group plc is a British aerospace, defence and nuclear engineering services company based in London, England. It specialises in managing complex assets and infrastructure. Although the company has civil contracts, its main b ...

(with whom former operators

VT Communications VT Communications was a part of VT Group plc. VT Communications was essentially the company formed from the privatisation of the BBC World Service transmitter sites. It was initially named Merlin Communications, then, after acquisition by VT, ...

are now merged). It has three transmitters: one

VLF Very low frequency or VLF is the ITU designation for radio frequencies (RF) in the range of 3–30 kHz, corresponding to wavelengths from 100 to 10 km, respectively. The band is also known as the myriameter band or myriameter wave a ...

; one LF; and an eLORAN transmitter. It is on the site of the

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 ...

military airfield which was operated by the

Fleet Air Arm The Fleet Air Arm (FAA) is one of the five fighting arms of the Royal Navy and is responsible for the delivery of naval air power both from land and at sea. The Fleet Air Arm operates the F-35 Lightning II for maritime strike, the AW159 Wil ...

as HMS ''Nuthatch''.

RNAS Anthorn

John Laing & Son began building an airfield at Anthorn for the

in late 1943, and Royal Naval Air Station, Anthorn, was commissioned as HMS ''Nuthatch'' on 7 September 1944, with three

tarmacadam Tarmacadam is a road surfacing material made by combining crushed stone, tar, and sand, patented by Welsh inventor Edgar Purnell Hooley in 1902. It is a more durable and dust-free enhancement of simple compacted stone macadam surfaces invented b ...

runways. It was the base of No. 1 Aircraft Receipt and Despatch Unit (No. 1 ARDU), which had the job of receiving aircraft fresh from manufacturers, modifying them to Service standards and despatching them to operational squadrons, with the unit specialising in the

Vought F4U Corsair The Vought F4U Corsair is an American fighter aircraft which saw service primarily in World War II and the Korean War. Designed and initially manufactured by Chance Vought, the Corsair was soon in great demand; additional production contracts ...

, Supermarine Seafire,

Fairey Barracuda The Fairey Barracuda was a British carrier-borne torpedo and dive bomber designed by Fairey Aviation. It was the first aircraft of this type operated by the Royal Navy's Fleet Air Arm (FAA) to be fabricated entirely from metal. The Barracuda ...

and

Fairey Firefly The Fairey Firefly is a Second World War-era carrier-borne fighter aircraft and anti-submarine aircraft that was principally operated by the Fleet Air Arm (FAA). It was developed and built by the British aircraft manufacturer Fairey Avia ...

types. No. 1 ARDU continued to operate from Anthorn following the end of the

Second World War 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 ...

, while a number of Fleet Air Arm Squadrons were also based at the airfield in the immediate post war years. The airbase shut down in March 1958. The present road to Cardurnock runs partially along the airfield perimeter track.Delve 2006, pp. 33–35. Several firing butts, for synchronising aircraft machine guns, can still be seen on the seaward side of the road.

VLF transmitter

The VLF transmitter is used primarily for transmitting orders to submarines and transmits on 19.6 kHz with an output power of 550 kilowatts. reprinted o
IEEE website
/ref> Its

callsign In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a unique identifier for a transmitter station. A call sign can be formally assigne ...

is GQD. VLF transmissions are relatively unaffected by atmospheric nuclear explosions and Anthorn was once part of the link between Fylingdales early warning radar, North Yorkshire, and the United States'

air defence system Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...

. A large part of the site is taken up by the VLF transmitter's large trideco wire

umbrella antenna An umbrella antenna is a capacitively top-loaded wire monopole antenna, consisting in most cases of a mast fed at the ground end, to which a number of radial wires are connected at the top, sloping downwards. They are used as transmitting antennas ...

. This consists of a central mast with 6 vertical wire radiators suspended from its top fed at the base of the mast, attached to 6 rhombic-shaped 2148 ft long horizontal multiwire toploads which radiate from the central mast at angles of 60°, supported by 12 surrounding masts, giving the antenna the shape of a 6-pointed star when seen from above. The cables supporting the endpoints of the wire antenna carry a load of 31 tons and are attached to computer controlled winches which automatically adjust the tension. The high voltage of several hundred kilovolts on the topload wires during transmission requires long strings of insulators where the wires are attached to the towers. It is a

NATO The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental military alliance between 30 member states – 28 European and two No ...

facility, controlled from

Northwood Headquarters Northwood Headquarters is a military headquarters facility of the British Armed Forces in Eastbury, Hertfordshire, England, adjacent to the London suburb of Northwood. It is home to the following military command and control functions: #Headqua ...

along with three other VLF transmitters in Norway, Germany and Italy. In accordance with the procedure for NATO projects, the project was the subject of a competition among the organisation's member countries. The British Post Office, acting as technical adviser and agent of the Ministry of Defence, chose the site, negotiated the contract and supervised the work, with the assistance of the

Ministry of Public Building and Works Ministry may refer to: Government * Ministry (collective executive), the complete body of government ministers under the leadership of a prime minister * Ministry (government department), a department of a government Religion * Christian mi ...

. The contract was placed on 26 October 1961 with Continental Electronics Systems Incorporated of Dallas, Texas. This firm had already built a similar but much larger station in Maine, USA. Work began in 1962 and the station was accepted on behalf of the MoD in November 1964. Originally, the station was designed to radiate a single telegraph channel at up to 45.5

baud In telecommunication and electronics, baud (; symbol: Bd) is a common unit of measurement of symbol rate, which is one of the components that determine the speed of communication over a data channel. It is the unit for symbol rate or modulatio ...

and at powers ranging from 50 kW at 16 kHz to 100 kW at 20 kHz. The

carrier frequency In telecommunications, a carrier wave, carrier signal, or just carrier, is a waveform (usually sinusoidal) that is modulated (modified) with an information-bearing signal for the purpose of conveying information. This carrier wave usually has a m ...

was to be stable to one part in 10⁸ over a month. Subsequently, the data rate was increased to 50 baud and the carrier stability improved.

LF transmitter: National Physical Laboratory time signal

The National Physical Laboratory (NPL) has installed three

atomic clock An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels. Electron states in an atom are associated with different energy levels, and in transitions betwee ...

s at Anthorn, and on 27 February 2007 Britain’s national time signal transmissions, retaining their original call sign of MSF, were transferred there on a trial basis, moving formally on 1 April 2007. The signals were previously transmitted from a transmitter at Rugby, administered by BT. The data transmitted includes time and date information which can be decoded using readily available software, and the signals are transmitted at an accurate frequency of 60

kHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that on ...

to provide a national

frequency standard A frequency standard is a stable oscillator used for frequency calibration or reference. A frequency standard generates a fundamental frequency with a high degree of accuracy and precision. Harmonics of this fundamental frequency are used to p ...

.. The transmitting aerial uses an auxiliary mast adjacent to the VLF array. Monitoring and logging of the clocks and control of the transmissions is by Internet link from the NPL offices at

Teddington Teddington is a suburb in south-west London in the London Borough of Richmond upon Thames. In 2021, Teddington was named as the best place to live in London by ''The Sunday Times''. Historically in Middlesex, Teddington is situated on a long m ...

, using comparison with

GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...

signals at both locations. Signal monitoring is by radio. To ensure accuracy, dynamic adjustment of the aerial according to local conditions (such as wind distortion) is controlled from computers on site. The effective radiated power is 17 kW.

LORAN

The general lighthouse authorities for Britain and Ireland have contracted VT Communications to develop eLORAN (enhanced LORAN) radio navigational aid for mariners. The transmitter is at Anthorn. The transmitting aerial uses an auxiliary mast adjacent to the VLF array. Due to the closure of the eLORAN service in Germany and Norway the eLORAN service was discontinued on 31 December 2015. However, the eLoran timing signal is still active to allow for research and support purposes.

Antenna system

The antenna system consists of thirteen masts, each tall, which are arranged in two rings around the central mast. The VLF antenna consists of four

rhombic antenna A rhombic antenna is made of four sections of wire suspended parallel to the ground in a diamond or "rhombus" shape. Each of the four sides is the same length – about a quarter-wavelength to one wavelength per section – converging but not to ...

s hung on large insulators on the masts, which are all grounded. The LF antenna is a

T-antenna A T-antenna, T-aerial, flat-top antenna, or (capacitively) top-loaded antenna is a monopole radio antenna with transverse capacitive loading wires attached to its top. T-antennas are typically used in the VLF, LF, MF, and shortwave bands, a ...

spun between two masts.

References

Sources

* * *

External links

Russell W. Barnes' page about the wartime history

Information on MSF relocation to Anthorn

Press release about MSF relocation to Anthorn

The Transmission Gallery: Anthorn
{{Royal Navy shore establishments Buildings and structures in Cumbria Transmitter sites in England Time signal radio stations NATO installations in the United Kingdom Military installations in England LORAN-C transmitters Military history of Cumbria