![CDAA Elmendorf AFB](https://upload.wikimedia.org/wikipedia/commons/3/3b/CDAA_Elmendorf_AFB.PNG)
The AN/FLR-9 is a type of very large circular "
Wullenweber
The Wullenweber (the original name introduced by Dr. Hans Rindfleisch was Wullenwever) is a type of Circularly Disposed Antenna Array (CDAA) sometimes referred to as a Circularly Disposed Dipole Array (CDDA). It is a large circular antenna array ...
"
antenna array, built at eight locations during the
cold war for
HF/DF
High-frequency direction finding, usually known by its abbreviation HF/DF or nickname huff-duff, is a type of radio direction finder (RDF) introduced in World War II. High frequency (HF) refers to a radio band that can effectively communicate ov ...
direction finding
Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio stati ...
of high priority targets. The worldwide network, known collectively as "Iron Horse", could locate
HF communications almost anywhere on Earth. Because of the exceptionally large size of its outer reflecting screen (1056 vertical steel wires supported by 96 towers), the
FLR-9 was commonly referred to by the nickname "Elephant Cage." Constructed in the early to mid 1960s, in May 2016 the last operational FLR-9 at
Joint Base Elmendorf-Richardson
A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...
in Alaska was decommissioned.
It can be confused with the US Navy's
AN/FRD-10
The AN/FRD-10 Circularly Disposed Antenna Array (CDAA) is a United States Navy circular "Wullenweber" antenna array, built at a number of locations during the cold war for high frequency radio direction finding (HF/DF) and signals intelligence. ...
, which also used a Wullenweber antenna.
Description
The ''AN/FLR-9 Operation and Service Manual'' describes the array as follows:
The antenna array is composed of three concentric rings of antenna elements. Each ring of elements receives RF signals for an assigned portion of the 1.5 to 30-MHz radio spectrum. The outer ring normally covers the 2 to 6-MHz range (band A), but also provides reduced coverage down to 1.5 MHz. The center ring covers the 6 to 18-MHz range (band B) and the inner ring covers the 18 to 30-MHz range (band C). Band A contains 48 sleeve monopole elements spaced apart (7.5 degrees). Band B contains 96 sleeve monopole elements spaced 37.5 feet (11.43 m) apart (3.75 degrees). Band C contains 48 antenna elements mounted on wooden structures placed in a circle around the central building. Bands A and B elements are vertically polarized. Band C elements consist of two horizontally polarized dipole antenna subelements electrically tied together, and positioned one above the other.
The array is centered on a ground screen 1,443 feet (439.8 m) in diameter. The arrangement permits accurate
direction finding
Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio stati ...
of signals from up to 4000 nautical miles (7408 km) away.
![ANFLR-9 antenna array](https://upload.wikimedia.org/wikipedia/commons/4/40/ANFLR-9_antenna_array.jpg)
FLR-9s were constructed at the following places:
*
USASA Field Station Augsburg
United States Army Security Agency (USASA) Field Station Augsburg was the site of a Wullenweber AN/FLR-9 (V8) radio direction finder, established during the Cold War. Field Station Augsburg was located on Gablingen Kaserne, near the village of G ...
(Gablingen Kaserne),
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
*
Chicksands
Chicksands is a village in the Central Bedfordshire district of Bedfordshire, England, and part of the civil parish of Campton and Chicksands, whose population in 2007 was estimated to be 2,510. By the 2011 census the figure was accurately place ...
,
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 ...
*
Clark AB
Clark Air Base is a Philippine Air Force base on Luzon Island in the Philippines, located west of Angeles City, about northwest of Metro Manila. Clark Air Base was previously a United States military facility, operated by the U.S. Air Forc ...
,
Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
*
Joint Base Elmendorf-Richardson
A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...
,
Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...
, USA (formerly designated as Elmendorf AFB)
*
Karamursel,
Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolian Peninsula in Western Asia, with a small portion on the Balkan Peninsula in ...
* 7th Radio Research Field Station/Ramasun Station,
Udon Thani Province
Udon Thani province ( th, อุดรธานี, ) is one of Thailand's seventy-six provinces (''changwat'') which lies in upper northeastern Thailand, also called Isan. It is bordered by the provinces of Nong Khai to the north, Sakon Nakhon ...
,
Thailand
Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is b ...
*
Misawa AB
is an air base of the Japan Air Self-Defense Force (JASDF), List of United States Air Force installations, the United States Air Force, and the United States Navy located in Misawa, Aomori, Misawa, Aomori Prefecture, Aomori, in the northern p ...
,
Japan, built 1963 to 1965, demolished beginning in 2014.
*
San Vito dei Normanni Air Station
San Vito dei Normanni Air Station was a United States Air Force facility located west of Brindisi, Apulia, between the port of Brindisi and the town of San Vito dei Normanni, Italy.
1960 - Base activated
Staffed by the 7275th Air Base Group, San ...
,
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
(near
Brindisi, Italy)
Advances in technology have made the FLR-9 obsolete. In 1997, the FLR-9 at the former Clark AB in the Philippines was converted into a
35,000-seat fabric-covered amphitheatre. In early May 2002, systematic dismantling of the FLR-9 at San Vito began, and it was totally deconstructed by the end of that month. Although the markings of where the array stood remain in the ground, the structure is completely gone.
Demolition of the FLR-9 at Misawa began in October 2014.
[ Kyodo News,]
'Elephant Cage' antennas to be axed
, ''The Japan Times
''The Japan Times'' is Japan's largest and oldest English-language daily newspaper. It is published by , a subsidiary of News2u Holdings, Inc.. It is headquartered in the in Kioicho, Chiyoda, Tokyo.
History
''The Japan Times'' was launched b ...
'', 8 October 2012, p. 2
A decommissioning ceremony for the last active FLR-9, at
Joint Base Elmendorf-Richardson
A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...
, was held on May 25, 2016.
See also
*
Signals intelligence
*
High-frequency direction finding
High-frequency direction finding, usually known by its abbreviation HF/DF or nickname huff-duff, is a type of radio direction finder (RDF) introduced in World War II. High frequency (HF) refers to a radio band that can effectively communicate over ...
References
External links
AN/FLR-9 Operation and Service manualUSASA Field Station Augsburg– history of the Augsburg site
* FLR-9 at Ramasun Station, Udon Thani, Thailand
* FLR-9 at Elmendorf AFB, Alaska
* FLR-9 at Gablingen, Augsburg, Germany
* FLR-9 at Misawa, Honshū Island, Japan
* FLR-9 site at Chicksands, Bedfordshire, UK
* FLR-9 site at Clark AFB, Philippines
* FLR-9 site at Karamursel AS, Turkey
* FLR-9 site at San Vito dei Normanni AS, Italy
FLR-9 photo collection on FTVA.org
{{DEFAULTSORT:AN FLR-9
Automatic identification and data capture
Military radio systems of the United States
Radio frequency antenna types
Radio-frequency identification
Surveillance
Military electronics of the United States
Antennas (radio)