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AN/ULQ-6

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USS New Jersey, with large ULQ-6 ECM system antenna on her fire control tower.

The AN/ULQ-6 was an electronic countermeasure (ECM) deception repeater and false-target generator used by the United States Navy,[1] primarily on destroyers and frigates.[2] It was often used in combination with the AN/WLR-1 countermeasures receiver, and both were replaced by the AN/SLQ-32 electronic warfare suite.[2][3] The ULQ-6 was also used by the Brazilian Navy on Marcílio Dias and Mato Grosso-class destroyers, Royal Canadian Navy on Iroquois-class destroyers,[4] Republic of Korea Navy on Chungbuk and Gangwon-class destroyers.

In accordance with the Joint Electronics Type Designation System (JETDS), the AN/ULQ-6 designation represents the 6th design of an Army-Navy electronic device for a general utility countermeasures special/combination system. The JETDS system also now is used to name all Department of Defense and some NATO electronic systems.

Technical description

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There are several different electronic jamming techniques. Among them, the ULQ-6 employs deception repeater jamming and false-target generation. Commonly referred to as digital radio frequency memory (DRFM),[5] the jammer digitizes characteristics of the threat radar, stores them, then uses those to broadcast back to the threat radar in deceptive ways. In the case of the AN/ULQ-6, the received signal was amplified, when transmitted back to the threat radar, to a power density equivalent to that of a capital ship like an aircraft carrier.[6] In this way, the smaller ship with the ULQ-6 repeating jammer would appear to the threat radar as a much larger target ship.[6]

Typically, two ULQ-6 systems were employed on a ship at opposing sides, 180° from each other. The combined antennas of the two provided doughnut shaped patterns covering a 360° azimuth around the ship.[6] The antenna section of each system had fixed donut-shaped upper and lower elements, with a trainable array element between them. This allowed the creation of a scannable beam in addition to a full-circle interference beam. Initially, it was only capable of operating in the 7–11 GHz (4.28–2.73 cm)[6] range (I-band), but later was expanded to cover the 4–8 GHz (7.49–3.75 cm) range (G and H-bands).[5][a]

Each AN/ULQ-6 was paired with the AN/WLR-1 electronic support measures radar warning receiver, widely deployed in the fleet at the time. The combination ULQ-6/WLR-1 sampled incoming signals at a rate of 4 Mbps, representing amplitude characteristics by 4 bits, resulting in an instantaneous bandwidth of 10–550 MHz across an expanded operational spectrum of 2–18 GHz (14.99–1.67 cm).[5]

History

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Adapted in 1959 from the AN/ALQ-32 airborne ECM system, the ULQ-6 for ships was envisioned as a countermeasure against Soviet anti-ship missiles like the SS-N-2 Styx or the AS-1 Kennel.[7][5] Originally operating at frequencies from 8–10 GHz (3.75–3.00 cm), the jamming system eventually covered from 4–10 GHz (7.49–3.00 cm) in all.[5] The system remained an integral part of fleet ECM through the 1970s, and was teamed up with the AN/WLR-1 electronic support measures radar warning receiver.[5]

The system was improved over time, available in three versions:[5]

  • AN/ULQ-6A — The first model having a peak transmit power of 1 kilowatt with the ability to create false targets, and functioned as a track breaker.
  • AN/ULQ-6B — Late 1960s saw an improved version, featuring range gate pull-off (RGPO) functionality causing range errors to threat radars, and an increased peak transmit power of 25 kW (average 1 kW).
  • AN/ULQ-6C — An improved model with a narrower transmission beam, provided to aircraft carriers and other capital ships, to make them appear to be smaller less appealing targets.

By the mid-1970s, the system was upgraded to the AN/SLQ-30, adding a channelized SLR-12 receiver and a spinning direction finding antenna to the ULQ-6B and ULQ-6C systems.[5] However, it was thought that outdated systems such as this were becoming increasingly difficult to counter the growing threat of modern anti-ship missiles. In May 1977, an order was placed for the development of the Raytheon AN/SLQ-32, a modular, commonly designed radio detection and jamming system, which began service in 1979. Many of the ships equipped with the ULQ-6 jammer were gradually converted to the SLQ-32.[5]

By 1990, the Government Accounting Office reported US$38 (equivalent to $93.64 in 2025) million worth of ULQ-6 assets were stored in Navy supply systems after removal from the fleet.[8] Installed in the early 1990s, aboard the Royal Canadian Navy's Iroquois-class destroyers, the ULQ-6 were replaced in 1999 by Shield and Nulka decoy systems.[9]

See also

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Notes

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  1. ↑ The terms G/H/I-bands are outdated NATO terminology for the bands. In more modern usage, Institute of Electrical and Electronics Engineers (IEEE) terms are more commonly used. Thus, G/H/I-bands together cover the IEEE's C- and X-bands

References

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  1. ↑ Polmar, Norman (November 1979). "The U. S. Navy: Electronic Warfare (Part 2)". United States Naval Institute. Retrieved November 17, 2025.
  2. 1 2 "AN/ULQ-6". Military Periscope.com. Retrieved November 12, 2025.
  3. ↑ Pike, John; Sherman, Robert (June 30, 1999). "AN/SLQ-32 Electronic Warfare (EW) system". FAS Military Analysis Network. Retrieved November 18, 2025.
  4. ↑ "Iroquois 280 Class and Trump Details". JProc.ca. February 28, 2024. Retrieved November 12, 2025.
  5. 1 2 3 4 5 6 7 8 9 Friedman, Norman (1997). The Naval Institute guide to world naval weapon systems 1997-1998. Annapolis, Maryland: Naval Institute Press. p. 556. ISBN 1557502684.
  6. 1 2 3 4 Jesswein, A J; Lesko, N J (March 18, 1966). NRL-MR-1682 Broadbeam ECM Antennas for Destroyer Installations (PDF) (Report). Washington, D.C.: US Naval Research Laboratory. pp. 1, 2, 6. doi:10.21236/AD0371638. DTIC AD0371638. Retrieved November 12, 2025. (19 pages)
  7. ↑ Analysis 2 - The Market for Surface Electronic Warfare Systems - Archived 2/98. Forecast International.com (Report). February 1997. p. 6. Retrieved November 17, 2025. In the late 1950s, the US Navy received the ULQ-6 false target generator to protect against missile attack. The design and operational doctrine of these systems was weak; they were difficult to use and were of limited effectiveness. In fact, their use was considered by many commanders to increase the chance of attack.
  8. ↑ Conahan, Frank C (March 1990). GAO/NSIAD-90-111 Defense Industry: Growth in Ship and Submarine Parts (PDF) (Report). Washington, D.C.: Government Accounting Office. p. 43. Retrieved November 17, 2025. Examples of these include 538 million in assets from the AN/ULQ-6 electronic warfare system, which was replaced by the AN/SLQ-32;
  9. ↑ "Career of the Tribals". Naval-Encyclopedia.com. 2025. Retrieved November 18, 2025.
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