The LANTIRN (Low-Altitude Navigation and Targeting Infrared System for Night) is a two-pod system fitted to F-15 Eagle and F-16 Fighting Falcon aircraft. It can also be operated by any aircraft that has a MIL-STD-1553B digital databus/multiplexer.
LANTIRN permits an aircraft to fly at very low levels at night or in limited-visibility conditions and conduct attacks with no external targeting data provided. Single-pilot operation is possible because of the high degree of automation and the integrated symbology. The pods are fitted under the engine intakes in both the F-15 and F-16.
The AAQ-13 is the navigation pod. It is fitted with a Texas Instruments J-band Terrain-Following Radar (TFR) that can be set in any one offive radar modes: manual TFR flight at preset altitudes from 1,000 ft (305 m) to 100 ft (30.5 m); Very Low Clearance (VLC) mode; weather mode permitting TFR flight in rain or othervisible moisture; the Low Probability of Intercept (LPI) mode, designed to reduce detectability; and Electronic Coun-ter-Countermeasures (ECCM) mode, which emphasizes immunity to ECM.
The navigational Forward-Looking Infrared (FLIR) has a selectable Field of View (FOV), using a wide, 6° FOV or the narrow, more precise 1.7° FOV. The FLIR can look into a turn or have its FOV offset 11° to either side for a “snap-look.”
The AAQ-14 is the targeting pod and is also fitted with its own ECU (Electronic Control Unit) and pod control computer. The nose section rolls to allow targeting by the gimballed FLIR and Litton Laser Systems Laser Designator Rangefinder (LDR) in a wide range of flight attitudes. The FLIR has a selectable FOV and is capable of precision pointing and automatic tracking of designated targets; space and weight provisions have been made for an automatic target recognition capability.
A typical night-attack mission uses the targeting pod first by displaying a wide FOV image on the pilot’s Head-Down Display (HDD). He switches to a narrow FOV for magnification and activates on the LDR. A Hughes missile boresight correlator allows the pod’s targeting data to be handed off automatically to the Maverick’s seeker. The LDR is also used as a target marker for LGB and as a range-finder for unguided, free-fall ordnance.
Sharpshooter is the targeting pod without the IR missile boresight correlator that is used with the Maverick IR missile.
Pathfinder is the simplified FLIR pod for close-air support missions in night or adverse weather conditions. Main component is the steerable, navigational
FLIR from LANTIRN with dual FOV. It
can be integrated with any aircraft
equipped with MIL-STD-1553B digital
databus and stroke/raster HUD.
Development began in 1980 by Martin Marietta in Orlando, Florida. US Air Force flight tests began in 1983 and totaled over 2,800 hours by the end of 1988. Development of the targeting pods experienced delays due to inability to meet AF performance requirements. As a result, the targeting pods began production at a slower rate than the navigational pods.
The first production navigation pod was delivered in April 1987; delivery of the first production targeting pod was delayed until June 1988.
Sharpshooter pods have been exported to Israel and Pathfinders to Egypt.
Full LANTIRN outfits have been sold to the Turkish and South Korean air forces.
LANTIRN II is an upgraded version of the LANTIRN in development since late 1989. LANTIRN II is designed to be located in the nose of the aircraft. The system’s dual-aperture design combines the navigation and targeting capabilities, and the system is guided by a head-steered helmet-mounted display.
COMBAT EXPERIENCE •
LANTIRNs were deployed with the two squadrons of F-15Es that flew against Iraqi targets during Operation Desert Storm and were considered a great success. The combination of the aircraft’s APG-70 radar, the navigation and targeting pods, and Paveway-series LGBs resulted in very precise strikes against bridges, command-and-control links, road networks, armored formations, airfields, and fixed and mobile Scud Tactical Ballistic Missile (TBM) sites by two-aircraft teams.
These teams consisted of one aircraft flying with both the navigation and targeting pod and the other carrying only the navigation pod (because of targeting pod shortages). Each aircraft carried eight GBU-12 500-lb (227-kg) LGBs; in
some attacks, all 16 bombs were put on their targets, according to the Air Force.
72 F-16s carried only the navigation pod, which was credited with significantly
expanding the aircraft’s night and adverse-weather capability. According to
the US Air Force, LANTIRN reliability on
these aircraft was over 98%. SPECIFICATIONS •
6 ft 6.2 in (1.99m)
8 ft 2′/2 in (2.5 m)
12 in (305 mm)
15 in (381 mm)
The AN/APG-63 multimode radar was developed for the F-15 Eagle fighter. The pulse-Doppler system uses a planar-array antenna and can operate on several selectable frequencies. The reliability goal of a 60-hour Mean Time Between Failures (MTBF) has proved elusive. In recent years, the average MTBF was 30—35 hours.
Four air-to-air modes include a search mode and three air-combat modes. Su-persearch is the least discriminating, locking onto the first target to enter the F-15′s Head-Up Display (HUD) field of view and marking it for the pilot. Vertical scan searches the vertical axis ahead of the aircraft. In the boresight mode, the antenna looks straight ahead and the radar notes any target coming into that cone.
The air-to-ground modes are ground mapping, an Inertial Navigation System (INS) velocity update mode, and an automatic bomb-release mode. The system also has Identification Friend or Foe (IFF) capability and automatic target acquisition out to lOnm (11.5 mi; 18.5km).
Hughes introduced a programmable signal processor with 96 kilobytes of memory in 1979 to improve ground map-
ping and close formation target discrimination capabilities. Further software updates provide Track-While-Scan (TWS) and compatibility with the AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM).
The APG-63 also flies in US Customs Service P-3A Orion maritime patrol craft for use against drug smugglers.
APG-63 MSIP included more memory and a programmable signal processor as part of the F-15 Multi-staged Improvement Program (MSIP).
APG-70 is the production version of a greatly enhanced APG-63 design; see APG-70 entry.
Production began in the early 1970s and ended in September 1986; manufactured by Hughes Aircraft Co.’s Radar Systems Group, Los Angeles, California. In service in US, Israeli, Japanese, and Saudi Arabian F-15s and in US Customs Service P-3s.
The AN/APG-65 is the digital multimode radar in the US Navy’s F/A-18 Hornet strike fighter. It can be used with the Sparrow and Sidewinder missiles and the 20mm gun for air-to-air combat, and a variety of conventional and guided weapons for ground attack.
The system consists of five Line-Replaceable Units (LRU) including an elliptical, flat-plate, electrically driven planar-array antenna that has low side-lobes for better Electronic Counter-measures (ECM) resistance.
Two of the LRUs are a liquid-cooled, gridded Traveling Wave Tube (TWT) transmitter and a Receiver/Exciter that houses the analog-to-digital converter and uses Field-Effect Transistors (FET).
A general-purpose Radar Data Processor (RDP) has a 250,000-word 16-bit bulk storage memory. The digital Programmable Signal Processor (PSP) operates at 7.2 million operations per second.
The radar has a large variety of air-to-air and air-to-surface modes. In the air-to-air mode, the APG-65 presents a clean display in both look-up and look-down conditions and has all-aspect target detection. The radar can perform velocity search, Range-While-Search (RWS), monopulse single-target tracking, Track-While-Scan (TWS) of up to 10 targets simultaneously, raid assessment to distinguish among closely spaced targets and gun director using pulse-to-pulse frequency agility for short-range sighting for the 20-mm cannon. The short-range Air-Combat Maneuvering (ACM) target acquisition modes are displaying a target in the Head-Up Display (HUD) and vertical and boresight acquisition.
Surface-attack modes include real-beam ground mapping, Doppler beam sharpening, terrain avoidance, precision velocity update for the Inertial Navigation System (INS), sea surface search, air-to-surface ranging, fixed or moving target tracking, and a synthetic aperture mode.
Testing began in the mid-1970s, with the radar achieving initial operational capability in 1981. Manufactured by Hughes Aircraft Co., Radar Systems Group, El Segundo, California.
In addition to equipping most
F/A-18s, the APG-65 replaced the AN/ APQ-120 radar in German F-4F Phantoms under the Improved Combat Effectiveness (ICE) program. AV-8Bs of the US Marine Corps and the Spanish and Italian air forces are being fitted with a modified APG-65 with a smaller antenna; the first of these was delivered in the summer of 1993.
Extensive updates have resulted in the
WEIGHT 450 Ibs (204 kg) VOLUME OCCUPIED less than 14.8 ft3 (0.42 m3)
The AN/APG-66 is a pulse-Doppler radar designed specifically for the F-l 6 Fighting Falcon fighter aircraft. It was developed from Westinghouse’s WX-200 radar and is designed for operation with the Sparrow and AMRAAM medium-range and the Sidewinder short-range missiles. It is less capable than the F/A-18′s APG-65 radar but weighs less, occupies less space, and is less expensive to acquire.
APG-66 uses a slotted planar-array antenna located in the aircraft’s nose and has four operating frequencies within the I/J band. The modular system consists of the antenna, transmitter, low-power Radio Frequency (RF) unit, digital signal processor, computer, and control panel.
The system has 10 operating modes, which are divided into air-to-air, air-to-surface display, and submodes. The air-to-air modes are search (with Track-While-Scan/TWS) and engagement, each mode having several variations. Six air-to-surface display modes include real-beam ground map, expanded real-beam ground map, Doppler beam sharpening, beacon, and sea. APG-66 also has engagement and freeze submodes. Antenna size varies from the pocket version in New Zealand’s upgraded A-4s to the larger-than-average APG-66J antenna in Japanese F-4EJs.
The system’s displays include the control panel, Head-Up Display (HUD), and radar display, with all combat-critical controls integrated into the throttle grip and sidestick controller.
Line-Replaceable Unit (LRU) modularity allows for shortened Mean Time to Repair (MTTR), since they can simply be replaced, involving no special tools or equipment. Westinghouse claims a 115hour Mean Time Between Failure (MTBF), although the service average is 97 hours in service.
First design work began in the late 1960s, progressing to the WWX-200 in 1972. Development of the APG-66 began in 1975, with the radar achieving initial operational capability in 1979 in the F-16.
Besides the F-16, the A-4 Skyhawk (APG-66NZ), Japanese F-4EJ Phantom (APG-66J), and the British single-seat Hawk 200 carry the APG-66. Antidrug-patrolling aircraft such as the US Customs Service Cessna Citation Us (six) and Piper Cheyenne (eight) as well as the Coast Guard’s modified HU-25A Guardian aircraft. The APG-66 is the primary sensor of the Small Aerostat Surveillance System (SASS) as well, but the antenna is a solid banana-peel reflector.
BAND I/J RANGE
downlook 26 nm (30 mi; 48 km) uplook 39 nm (45 mi; 72 km)
PEAK POWER INPUT 3.58 kW SYSTEM WEIGHT 296 lb (134.3 kg) SYSTEM VOLUME 3.6 ft3 (0.102 m3) ANTENNA BEAMWIDTH 3.2° X 4.8° ANTENNA DIMENSIONS
length 2 ft 5 in (0.74 m)
width 1 ft 7 in (0.48 m)
MAX SCAN IN AZIMUTH 60° either side
of vertical centerline MAX SCAN IN ELEVATION 60° above or
below horizontal centerline
The AN/APG-66(V) is a variant of the
APG-66 pulse-Doppler radar with a Line-Replaceable Unit (LRU) containing the Signal Data Processor (SDP) that replaced the APG-66′s computer and digital signal processor. The SDP performs
their combined functions with increased memory, throughput capacity, and processing speed. APG-66(V)’s detection range is 20% greater than that of the APG-66.
The system has all of APG-66′s operational modes and includes an additional
12 modes: Track-While-Scan (TWS),
dual-target situational awareness, interleaved map, weather avoidance, advanced situation awareness, high accuracy track, Ground Moving Target Indication (GMTI), Ground Moving Target Track (GMTT), maritime target track, multitarget attack/reattack, High-Resolution Map Along Track (HRMAT), and Doppler Beam Sharpening (DBS).
DEVELOPMENT • Manufactured by Westinghouse Electronic Systems Group, Baltimore, Maryland. Intended primarily for export.
PEAK INPUT POWER 2.204 kW SYSTEM WEIGHT 240 lb (108.9 kg) SYSTEM VOLUME 2.91 ft3 (0.08 m3)
GD-53 (APG-67) Golden Dragon
The AN/APG-67(V) multimode radar is a relatively lightweight and short-range system that fits into a small volume. Despite its merits, the APG-67 series has been unsuccessful in F-5A/E refit competitions. Only a derivative of the APG-67(C), which shares 90% commonality with the -67 (F), met with success, being developed for the Taiwanese Ching Kuo Indigenous Defense Fighter (IDF) as the GD-53 Golden Dragon.
The APG-67 is a coherent pulse-Doppler system that uses a flat-plate, vertically polarized, slotted array antenna on a direct-drive, two-axis balanced-gimbal mount. The transmitter has variable output power, pulse widths, and Pulse Repetition Frequencies (PRF).
The radar data computer contains two MIL-STD-1750A central processing units that can execute 256-point Fast Fourier Transform (FFT) coherent integration. It can be integrated into an avionics system through an MIL-STD-1553B digital databus interface and has Built-in Test (BIT) capability.
Air-to-air modes include Range-While-
Search (RWS), Velocity Search (VS), Adaptive Search Mode (ASM), air-combat (four submodes) Single-Target-Track (STT), Situational Awareness
Mode (SAM), and Track-While-Scan (TWS).
Air-to-ground modes include Real-Beam Ground Mapping (RBGM), Dop-pler Beam Sharpening (DBS), and surface moving target indication.
APG-67 (E/F) is the export-oriented variant with lower weight, smaller antenna for the F-5E/F.
Golden Dragon GD-53 is Extended-Range Radar (ERR) APG-67 (C) variant for operation in Taiwanese Ching Kuo IDF.
Development of the APG-67 began in the late 1970s for the Northrop F-20 Tigershark (formerly F-5G) aircraft, using technology derived from the Modular Survivable Radar (MSR) program. After the F-20′s cancellation, GE developed the APG-67 (E)
and (F) for retrofit to non-US F-5 Freedom Fighter/Tiger aircraft. The only production version, however, is the GD-53 fitted in Taiwan’s IDF.
PEAKPOWER -67(E)/(F) 3.5 kW TRANSMIT POWER -67 (V) 200 watts; -67(E)/(F) 160 watts
RANGE, APG-67 (F)
RWS, look-up: 27-31 nm (31.1-35.7 mi;50-57.4km)
RWS, look-down: 17-21 nm (19.624.2 mi; 31.5-39.9 km) Air Combat: 10 nm (11.5 mi; 18.5
SMTI, patrol craft, sea state 4: 26 nm (29.9 mi; 48.2 km); tank 19 nm (21.9 mi; 35.2 km) WEIGHT, -67(F) 189 Ib (86 kg) SYSTEM VOLUME 2.1 ft3 (0.060 m3)
ANTENNA SIZE, -67(F)
height 11 in (279 mm)
width 17 in (432 mm)
The AN/APG-68 radar is derived from the AN/APG-66 but is substantially improved, making it capable of supporting the AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM). It supports the expansion of the F-16′s mission from day fighter to multirole aircraft. Performance improvements include increased range; sharper resolution, especially in the ground-mapping modes; and the addition of several modes.
Other improvements include a grid-ded, multiple peak power Traveling Wave Tube (TWT) transmitter and programmable signal processor possessing a block-oriented, random-access 386K-word nonvolatile memory.
In the air-to-air mode, the APG-68 can perform velocity search, look-up search,
Range-While-Search (RWS), Track
While-Scan (TWS) up to 10 targets simultaneously, raid assessment, and gun director, and three short-range Air-Combat Maneuvering (ACM) target acquisition modes including displaying a target in the Head-Up Display (HUD) as well as vertical and boresight acquisition.
Surface-attack modes include real-beam ground mapping with scan freeze, Doppler beam sharpening, terrain avoidance, terrain following, sea surface search, air-to-surface ranging, fixed and moving target tracking, and beacon homing.
The APG-68 also has improved Electronic Counter-Countermeasures (ECCM) including reduced sidelobes.
Upgrading of APG-66 design began in 1978, with the radar achieving initial operational capability in 1985. Manufactured by Westinghouse Electric Corp., Baltimore, Maryland. Fitted only to the F-16C/D Fighting Falcon; however, the APG-66(V) uses many ofthe same components and is intended for export. See APG-66(V).
The AN/APG-70 is an improved version of the AN/APG-63 attack radar designed for the F-15E Eagle fighter aircraft. The system has improved software and hardware, with all hardware conforming to
MIL-STD-1750A architecture. APG-70 also has growth provisions for increased memory capacity, processing speed, and mode enhancements.
Air-to-ground modes include precision velocity update and air-to-ground ranging. The APG-70 permits the crew, flying at a low altitude, to pick out targets from distances over 73 nm (80 mi; 135 km). It can freeze images of a particular area, allowing the radar to be turned off so the aircraft can close in on the target without being detected through its radar emissions. The APG-70′s air-to-ground weapons delivery and high-resolution mapping modes can only be accessed by those F-15C/D and F-15E aircraft that have dual-role capability.
The system uses Synthetic Aperture Radar (SAR) imagery for better resolution in the real-beam ground mapping and high-resolution ground mapping modes. The original resolution specification of 8.5 ft (2.6 m) resolution at 20 nm (23 mi; 37 km) range was met and may have been surpassed.
The APG-70′s search modes in the air-to-air role are Range-While-Scan (RWS) and velocity search. Three RWS modes use high, medium, or interleaved Pulse Repetition Frequency (PRF). The APG-70′s Track-While-Scan (TWS) mode is accessed once targets are sorted. Other modes in the air-to-air role are single-target track, raid-assessment track, vertical search, super search, boresight, and auto-gun target acquisition modes.
AN/APG-80 is the modified version of the APG-70 for the Air Force’s AC-130U Spectre special-operations aircraft by Hughes Aircraft. Five additional operational modes: fixed target track, ground moving target indication and tracking, projectile impact point position, beacon track, and a weather mode for firing in poor visibility. Upgrades also include a digital scan converter and modifications to the APG-70 signal processor and antenna.
capability in 1986, with flight tests beginning in 1986 and continuing through mid-1988. The first production system was delivered in December 1986, and the first production APG-70-equipped F-15C/D was delivered in June 1987.
APG-70 is part of the Multistaged
Improvement Program (MSIP) for the
F-15, replacing the AN/APG-63 already installed in the aircraft. Retrofitted into approximately 39 F-15C/D and approximately 392 F-15E aircraft. Manufactured by Hughes Radar Systems Group, El Segundo, California, with a coproduction agreement with Mitsubishi in Japan.
COMBAT EXPERIENCE •
During Operation Desert Storm, the APG-70 proved as effective as had been hoped, with many observers calling the F-15E/ APG-70 combination the best strike aircraft in the world. As an air-to-ground radar, its resolution was said to be excel-
lent over a long range. The radar was also reported to be very reliable.
The AN/APG-71 fire control radar is an upgrade of the AWG-9 weapons control system used in the US Navy F-14 Tomcat. It also shares 86% of the Shop-Replaceable Assemblies (SRA) with the
APG-70 flown in the F-15C/E. The APG-71 is basically a digital version ofthe AWG-9 but represents a reworking of virtually every part of the system; only the transmitter, power supply, and aft cockpit tactical information display are retained from the AWG-9. Detection and tracking ranges increase by 40%, while reliability is expected to double in hours between failures.
A new broadband radar master oscillator contributes to improved Electronic Counter-Countermeasures (ECCM) capabilities. The analog-to-digital converter is claimed by Hughes to be state-of-the-art. The antenna control allows for more flexible search patterns than those of the AWG-9.
The fully programmable, four-unit signal processor and improved radar data processor permit greater simultaneous coverage of opening (target moving away) and closing (target heading toward aircraft) speeds. Additional modes permit Beyond Visual Range (BVR) target identification, raid assessment with high-resolution Doppler techniques to distinguish among closely spaced targets, monopulse angle tracking to predict the future position of a single target during high-speed maneuvers, and distortionless sector ground mapping of both ocean and land areas.
The APG-71 can also be linked to Infrared Search and Tracking (IRST) for passive, long-range search making little
use of the active radar. Digital scan control and improved frequency agility are also part of the upgrade.
The advanced low-sidelobe antenna is more difficult to jam. Its mount is different, but the antenna retains the gimbal system used in the AWG-9.
Further improvements planned or proposed for the APG-71 cover virtually every operational facet. Budget stringencies battle with the newly enhanced air-to-ground role envisioned for the F-14 to determine which shall be funded. They include:
• adding a medium Pulse Repetition Frequency (PRF) capability for air combat maneuvering
• interleaving high- and low-PRF waveforms for improved detection at greater range
• modifying the frequency modulation of the ranging Doppler to operate over a greater range
• improving ground clutter definition and ground moving-target indication and tracking
• manual terrain avoidance and clearance
• improved look-down, shoot-down capability over land
• adding high-resolution synthetic aperture and inverse synthetic aperture modes
achieved initial operational capability in 1991. Manufactured by Hughes Aircraft, Radar Systems Group, in Los Angeles, California.
The AN/APG-73 is a US-Canadian program to greatly improve the F/A-18 Hornet’s APG-65 radar by retaining the transmitter and antenna, but updating the Receiver/Exciter and developing new components that replace the general-purpose Radar Data Processor (RDP) and digital Programmable Signal Processor (PSP). Better resolution, added modes, and better ECCM are some of the benefits.
Processing speed and power increases are considerable. The PSP’s speed jumps from 7.1 million complex operations per second to 60 million; spare capacity allows a later increase to 80 million. Memory capacity expands to one megaword in the PSP and two megawords in the RDP. RDP speed increases to 2 million instructions per second. Analog-to-digital converters also speed up several times.
A later phase upgrades Synthetic Aperture Radar (SAR) mode processing and a motion sensor subsystem that counteracts distortions from airframe bending that degrade accuracy in the current in-ertial reference unit. A third phase would introduce the active array antenna.
A $65.7-million Full-Scale Engineering Development (FSED) contract was awarded to McDonnell Douglas Aircraft (Hughes Aircraft is major subcontractor) in May 1990; later awards raised the value to $223 million. Five engineering development prototypes and the first 15 production sets were contracted for in 1991. Testing began in 1993, with first production delivery in June 1994.
All F/A-18s built for the US Navy after 1989 are to operate APG-73s as well as several foreign air force customers.
WEIGHT approx 450 Ibs (204 kg) VOLUME OCCUPIED less than 14.8 ft3 (0.42 m3)
The AN/APQ-122 (V) dual-frequency radar is part of the Adverse-Weather Aerial Delivery System (AWADS) used in the C-130 transport aircraft. The radar’s functions include long-range navigation, weather avoidance, and ground mapping.
In the (V)8 version, separate I-band and K-band receiver/transmitters feed a common solid parabolic antenna; the I-band transmitter can also energize a circular antenna used in Terrain Avoidance/Terrain Following (TA/TF) flight. (An additional “cross-scan” mode interleaves TA and TF in a time-sharing pattern.)
I-band is used for weather plotting, ground mapping, and ground beacon interrogation. K-band permits high-resolution ground mapping in adverse weather. APQ-122s received a Systems Research Laboratories scan converter in the late 1980s that converts radar range and bearing returns into signals suitable for high-resolution (1,024 X 810 pixels), raster-scan Cathode-Ray Tube (CRT) displays.
APQ-122 (V)l was fitted in C-130Es, APQ-122 (V) 5 was an I-band-only radar that replaced the AN/APN-59 in the C-130 and E-4B, and APQ-122 (V) 7 is used in navigation training in the T-43 aircraft, but is otherwise similar to (V)5.
units produced, 150 exported in C-130s. Being replaced by the ESCO AN/ APQ-175. Manufactured by Texas Instruments in Dallas, Texas.
BAND I and K
ground mapping: 200 nm (230 mi; 371 km)
weather information: 150 nm (173
mi; 278 km) beacon interrogation: 240 nm (276
mi; 444 km)
The AN/APQ-153 is a lightweight airborne fire control radar used in the F-5E aircraft. Its principal operational modes are search, boresight missile, and air-to-air gunnery.
In search mode, target detection range is 20 nm (23 mi; 37 km) and the search pattern is space-stabilized to counter aircraft pitch and roll to prevent loss of target. In the boresight missile mode, the pilot can acquire targets out to ten nautical miles for the AIM-9 Sidewinder missile.
The two heads-up air-to-air gunnery modes, one of which is for use in dogfights, automatically acquire the first target encountered and provide range and range-rate information to the sight for all targets.
Achieved initial operational capability in the early 1970s. Currently in use in the F-5E aircraft in several countries.
The AN/APQ-156 is a multimode airborne radar that combines into a single radar the A-6A Intruder’s AN/APQ-92 search and terrain-following radar and AN/APQ-112 target tracking and ranging radar.
The main antenna has an overhanging horn feed that generates a narrow beam with a cosecant-squared profile, reducing detectability and eliminating the need for the radar to scan in elevation. Modes include Track-While-Scan (TWS) and Airborne Moving Target Indicator (AMTI) processing, ground mapping, and beacon detection and tracking.
The APQ-156 radar added a Forward-Looking Infrared (FLIR) /laser Target Recognition Attack Multisensor (TRAM) system to the A-6E aircraft. An interferometer under the main parabolic reflector aids in terrain avoidance. In an antenna that is slaved to the main antenna in azimuth, 64 horns in two rows detect elevation changes along the aircraft’s route by comparing the differences in phase delays between the upper and lower rows.
Plans to upgrade the system met with program redirection and budgetary cutbacks.
AN/APQ-148 was the first version of the APQ-156. The AN/ APS-130 is similar but is fitted in the EA-6B Prowler EW aircraft.
The APQ-148 was delivered in 1971, and the APQ-156 followed in 1981. Some were used for retrofit into the A-6A. APQ-148 systems in older A-6Es were upgraded to APQ-156 standard. Manufactured by Norden Systems, Norwalk, Connecticut.
The AN/APQ-159(V) series is a family of forward-looking multimode pulse radars. Used in the search mode, the APQ-159(V) series has a range of up to 40 nm (74 km). For shorter search ranges, the system conducts a space-stabilized two-bar scan of the planar-array antenna using an 8°-wide beam.
In the missile boresight mode, used with the Infrared (IR)-seeking AIM-9 Sidewinder air-to-air missile, the radar
locks onto the target and provides steering information to bring the aircraft within the missile seeker’s boresight envelope. Off-boresight expands the radar’s target search envelope at longer ranges. For gunnery, the array locks into bore-sight and searches through a range gate of500-6,000 ft (152-1,830 m) at the rate
of 22,000 ft/sec (6,706 m/sec), automatically locking onto the first target it sees.
In the Electro-Optical (E-O) mode, the system operates the AGM-65 Maverick missile, relaying the image from the missile’s E-O seeker to the cockpit display.
A few of these radars were installed in MiG-21 Fishbed aircraft that the US acquired for evaluation.
APQ-159 (V) 1 – (V) 4 are variants, with differences in the number of controls and video indicators. APQ-159(V)5 is described as having a 100% increase in the maximum track/ acquisition range and a 100% increase in reliability. Used in “Red Flag” aggressor-squadron F-5Es.
Emerson Electric (later ESCO), St. Louis, Missouri. In February 1991, CESELSA, the Spanish electronics company, announced that it would be fitting Spanish Air Force Mirage HID and IIIE with the APQ-159; this raised export hopes, but that program was later canceled for budgetary reasons.
The AN/APQ-164 multimode, dual-channel, coherent pulse-Doppler radar is the Offensive Radar Subsystem (ORS) of the AN/ASQ-184 Offensive Weapons Control System of the B-l bomber. Unlike many of the other B-l systems, the
APQ-164 has encountered few service problems, possibly because it was derived from the proven AN/APG-68 radar flown in the F-16C/D Fighting Falcon.
Each channel of the APQ-164 has its own independent set of Line-Replaceable Units (LRU), which can back up the other set. The LRUs include a gridded, multiple peak power Traveling Wave Tube (TWT) transmitter, radar receiver/transmitter, and programmable signal processor, all originally developed for the APG-68, as well as a radar video signal processor.
The phased-array antenna has 1,526 phase control modules that can be scanned electronically in both axes to +/—60°. The dish can be locked into one of three positions (looking ahead or 45° to either side). When side-looking, the radar’s field ofview extends up to 105° aft of straight ahead.
The radar’s four basic functions are navigation and weather detection, penetration through low-level terrain following/terrain avoidance, weapons delivery, and rendezvous for air-to-air refueling.
Navigation uses the synthetic aperture mapping mode with real-beam ground mapping for high-resolution images as well as strip mapping when the radar is slewed to one side or the other.
Terrain avoidance is manual, but terrain following is automatic. In velocity update, the radar emits a narrow “flashlight” beam periodically (the periodicity depending on selection of a given clearance altitude out of 11, ride levels, and nature of terrain).
Moving Target Indicator (MTI) processing allows detection of moving targets within ground clutter, and Moving Target Track (MTT) establishes a track file. Other modes can provide updates to the bomb delivery system’s altimeter as well as target survey.
Air-to-air modes chiefly concern rendezvous for refueling, weather detection, and beaconing.
Derived from the
APG-68 and EAR series. Development began in 1981. Achieved initial operational capability in 1986. Manufactured by Westinghouse Electric, Baltimore, Maryland.
SYSTEM WEIGHT 1,257 lb (570 kg) ANTENNA DIMENSIONS
width 3 ft 8 in (1.12m) height 1 ft 10 in (0.56 m)
The APQ-169 is the latest of a series of forward-looking multimode attack radars flown in US Air Force F-l 11 strike aircraft. The system has been updated several times and has had several designators.
The air-to-air mode provides automatic range search, target acquisition and tracking, and plots angle tracks in a Track-While-Scan (TWS) mode. Air-to-air use is limited to the Infrared (IR)-guided AIM-9 Sidewinder missile, as the radar does not have a semiactive mode. The air-to-ground mode can be used for all-weather weapons delivery, navigational position fixing, and air-to-ground ranging.
The APQ-169 introduced pulse compression for better range resolution, a 0.25 pulse width, and a television raster-scan display. More important is the extensive reliability and maintenance upgrade that raised the mean time between failures substantially.
APQ-113 (F-111A/E and RAAF F-111C), APQ-114 (FB-111A),
APQ-144 (F-l 1 IF), APQ-161 (supports with AN/AVQ-26 Pave Tack electro-optical target designator system),
APQ-163 (modified APQ-144 used in the
B-1A bomber prototype program), APQ-165 (RAAF F-111C radar with Pave Tack and Harpoon antiship compatibility) .
DEVELOPMENT • Began in the mid-1960s for the APQ-113/114. The APQ-169 achieved initial operational capability in the mid-1980s. Manufactured by GE in Utica, New York.
PULSE WIDTHS 0.2, 0.25, 0.4, 1.2, or 2.4
microsec PRF 337-4,044 Hz
The AN/APQ-170 was developed for the MC-130H Combat Talon II to support low-level, adverse-weather Special Operations Command missions. It is actually a combination oftwo radars: a flat, circular I/J-band (old X band) antenna and back-to-back, solid truncated paraboloid J-band (old Ku band) reflectors. The mount is fitted in the MC-130H’s nose.
The I/J-band radar swivels through arcs of 90° horizontally, 75° vertically for terrain avoidance, terrain following, and beacon location. The J-band antennas rotate at up to 30 rpm for weather detection, ground mapping, and beacon location. If the J-band radars fail, the I/J-band system can take over weather detection and ground mapping.
Both radars are designed to see through rainfall, although at a reduced distance.
Software problems slowed acceptance of the APQ-170.
achieved initial operational capability in
1993. Manufactured by ESCO in St.
terrain avoidance/terrain following I/J
I/J-band at 250 ft (76 m) above
ground level, 20 nm (23 mi; 37 km); in 0.4-in (10-mm)/hr rainfall, 14 nm (16 mi; 26 km) J-band can see coastlines at 50 nm (58 mi; 93 km), towers at 5 nm (5.8 mi; 9.3km)
J-band radar beacon detection: 240
nm (276 mi; 444 km) J-band, severe-weather cell: 150 nm
(173 mi; 278 km)
The AN/APQ-171 is the latest version of a series of dual-channel, multimode, forward-looking radars fitted in the F-l 11 deep-strike aircraft. Earlier models of the APQ-171 were the APQ-110 for the
F-111A/C/E, APQ-128 for the F-111D, the APQ-146 in the F-l 1 IF, and the
APQ-134 for the FB-111. The APQ-171 is similar in function to the earlier versions but is more reliable and more easily maintained. Compared to the original radar, the APQ-171 is a 75% redesign, with reliability improving sixfold.
Each version has a pair of multimode, forward-looking radars using identical antennas. The Terrain-Following Radar (TFR) automatically keeps the aircraft at a preset ground clearance by signaling the flight control system. Other TFR modes are terrain avoidance, ground mapping, and situation.
If the AN/APQ-169 attack radar should fail, the weapons control system can use the APQ-171 as a backup ground-mapping system by using its transmitter to drive the APQ-169′s antenna. For air-to-ground ranging, the antennas are slaved to the lead-computing optical sight in elevation; their azimuth is corrected to the drift angle generated by the sight.
The APQ-110 entered service in the F-111A in 1967. After modifications to increase reliability and maintainability are completed, all earlier radars in the series are redesignated AN/ APQ-171. Manufactured by Texas Instruments in Dallas, Texas.
The AN/APQ-174 Multimode Radar
(MMR) was developed for the Special Operations Command MH-47E and MH-60K covert operation helicopters. It is based on the terrain-following radar found in the AAQ-13 navigation pod of the LANTIRN system. The small antenna means a relatively short range and lower resolution, but the APQ-174′s compactness and low weight suit it well for volume-limited aircraft such as the MH-60.
Like the LANTIRN radar, the MMR modes include manual Terrain-Following Radar (TFR) flight, Very Low Clearance (VLC), weather, Low Probability of Intercept (LPI), and Electronic Counter-Countermeasures (ECCM). In addition, the APQ-174 offers Terrain Avoidance (TA), Ground Mapping (GM), and air-to-air ranging. Also, the APQ-174 can interleave the TF and TA modes as well as the TF and GM modes.
First funding came in 1990, with production contracts being awarded in 1992. Initial operational capability was achieved in 1994.
The AN/APQ-175 is the successor to the
APQ-122 Adverse-Weather Aerial Delivery System (AWADS) radar set fitted in many C-130s. Like the AN/APQ-170, also produced by ESCO, the system combines two radars: an I/J-band (old X band) antenna for weather detection and long-range ground mapping and a K-band (old Ka band) for shorter-range precision ground mapping. The system also features dual independent high-resolution displays.
Both radars are designed to see through rainfall, although at a reduced distance.
First contracts awarded in mid-1980s for delivery of the first 50 production units beginning in 1990. The APQ-175 achieved initial operational capability in 1993. Manufactured by Electronics and Space Corp. (ESCO) in St. Louis, Missouri.
long-range ground mapping and weather I/J
precision ground mapping K
RANGE I/J band long-range ground mapping: 175 nm (202 mi; 324 km)
The B-2′sAN/APQ-181 radar emphasizes
Low Probability of Intercept (LPI) design and operation and features 21 pulsed or pulse-Doppler search, detection, and track modes as well as penetration and navigation Synthetic Aperture Radar (SAR) modes.
Each B-2 has two fully redundant radar systems, each with five Line-Replaceable Units (LRU) and a MIL-STD-1553 digital databus. All LRUs except the antenna can function for both radars if necessary. Each system has a liquid-cooled, gridded Traveling Wave Tube (TWT) transmitter, air-cooled receiver that performs pulse compression and generates RF waveforms, fully programmable Radar Signal Processor (RSP), and Radar Data Processor (RDP) that develops the beam-steering commands used by the antennas’ beam-steering computers.
The two liquid-cooled electronically scanned antennas are buried in the forward fuselage sides, each about 8 ft (2.44 m) from the aircraft’s centerline andjust behind the nose-gear compartment (which holds the other LRUs). Using a monopulse feed and steered in two axes, the radar achieves fractional beamwidth angular resolution. SAR operation requires correction for antenna movement, achieved through a Smiths Industries modified strap-down inertial platform.
Some modules were derived from the APG-70 and APG-71 fighter aircraft radars. The APQ-181 was first tested in the KC-135 Avionics Flight Test Bed (AFTB) in January 1987, amassing over 1,600 hours of operation— including more than 1,000 hours in 172 flights devoted to radar testing—up to January 1991.
Although the APQ-181 was tested on the first Air Vehicle (AV-1) to fly, the third, AV-3, is the avionics test bed. The radar is manufactured by Hughes Aircraft, Torrance, California.
BAND J (12.5-18 GHz)
system 2,100 Ib (953 kg)
antennas 575 Ib (261 kg) VOLUME 52.5 ft3 (1.49 m3)
The APS-115 is an airborne search radar used primarily for maritime patrol and Antisubmarine Warfare (ASW) operations. The system uses two antennas, one in the nose and one in the tail of the P-3C Orion aircraft. The antennas scan 45° sectors and can be tilted through a -207+10° arc.
Also part of the system are two transmitter/receivers, an antenna position programmer, dual set controls, and a common antenna control unit. Long pulses at relatively low scan rates and Pulse Repetition Frequencies (PRF) aid long-range search. For target classification at shorter ranges, the radar switches to a short-pulse, higher-scan, higher-PRF mode.
Achieved initial operational capability in 1969 in early P-3C aircraft. Manufactured by Texas Instruments.
PEAK POWER 143 kW
PULSE WIDTH 0.5 or 2.5 rmcrosec
PRF 1,600 or 400 Hz
SCAN RATE 12 or 6 rpm
SYSTEM WEIGHT 523 Ib (237 kg)
ANTENNA BEAMWIDTH 2.4° X 3.6°
The AN/APS-116 is a coherent, pulse-Doppler Antisubmarine Warfare (ASW) search radar designed to detect submarine periscopes and antennas in rough seas. It has been developed further as the export-oriented AN/APS-134 and the succeeding AN/APS-137(V), which has an added Inverse Synthetic Aperture Radar (ISAR) mode. The system’s scanner is mounted in a nose radome, and the radar is integrated with the aircraft’s data systems.
In its periscope-detection mode in high sea states, the radar uses high peak power, high scan rates (300 rpm) for high resolution, short pulse widths (2.5 nanoseconds), high Pulse Repetition Frequencies/PRF (2,000 Hz), pulse compression, and Moving Target Indicator (MTI) processing.
For navigation and surface search, the operator can select either a lower scan rate and low PRF with pulse compression for high resolution of maritime targets or Track-While-Scan (TWS) processing. A relatively slow scan rate, low PRF, and frequency agility serve for long-range search and navigation.
The APS-137 adds Inverse Synthetic
Aperture Radar (ISAR) processing in which the radar acts as a searchlight, “staring” at a given point on a target. Processing the Doppler shifts of other parts of the target due to roll and pitch motion generates a two-dimensional image. Range resolution is nominally 6 ft (1.8 m) but can be reduced to 1.5 ft (0.46 m). Up to 32 ships can be tracked simultaneously. Subvariants include APS-137(V)1 (S-3), APS-137 (V) 2 (P-3C Update III aircraft), APS-137(V)3 (P-3C Update IV), APS-137(V)4 (Coast Guard HC-130 Search and Rescue/SAR aircraft), APS-137(H) (helicopter-based system).
APS-116 achieved its initial operational capability in 1974. Manufactured by Texas Instruments, Dallas, Texas. APS-137 (V) is in production for P-3, S-3B.
BAND I (9.5-10 GHz) WEIGHT 472 Ib (214 kg)
The AN/APS-124 radar is fitted in the US Navy’s SH-60B Seahawk helicopter as part of the LAMPS III shipboard surveillance system. Designed primarily to detect submarine periscopes and masts, the APS-124 also searches for and acquires targets for antiship cruise missiles. It is not fitted in the SH-60F variant of this helicopter, which is the carrier-based model fitted with active dipping sonar, or other navalized SH-60 variants.
The APS-124 was configured for a “flat” radome that could be positioned under the forward fuselage of the SH-60. It is linked to other systems through its
MIL-STD-1553 digital databus. The planar-array antenna rotates up to 120 rpm. Images can be displayed in the helicopter while in flight as well as being data-linked to surface-ship displays.
Three data modes using different pulse widths and Pulse Repetition Frequencies (PRF) provide for long- and medium-range search as well as fast-scan surveillance. An OU-103/A digital scan converter performs scan-to-scan integration of the returns, helping to screen out clutter.
achieved initial operational capability in
the SH-60B in 1983. Manufactured by
Texas Instruments, Equipment Group, Dallas, Texas. All SH-60 operators use the APS-124.
WEIGHT 210 Ibs (95 kg)
RANGE TO DETECT A 10.8-FT2 (1-M2) TARGET 16 nm (18 mi; 30 km) PEAK POWER 350 kW PULSE WIDTH
long range: 2 microsec medium range: 1 microsec fast scan: 0.5 microsec
long range: 470 Hz medium range: 940 Hz fast scan: 1,880 Hz
ANTENNA BEAMWIDTH 1.2° X 20° ANTENNA DIMENSIONS
width 6 ft (1.83m)
height 1 ft (0.31 m)
APS-125 APS-138 APS-139
This series of radars is the principal sensor for the E-2C shipboard Airborne Early Warning (AEW) aircraft. It can track 300 targets simultaneously at ranges of about 250 nm (288 mi; 463 km). The system is mounted in later E-2C Hawkeye aircraft and has a 24-ft (7.93-m) diameter ro-todome mounted above the fuselage.
Some observers have contended that the APS-125 series radar system’s range and processing capability, while impressive in the 1970s when the earlier variants were introduced, lagged behind the threat in the 1980s and 1990s. In many scenarios, the E-2 has come to rely on the radars of the scouting interceptors it was designed to support for initial detection of the enemy. During Operations Desert Shield and Desert Storm, moreover, the system proved relatively limited and inflexible, especially in comparison to the E-3 AWACS and Aegis ship-based sensor systems.
The APS-125 evolved from the APS-120 system found in the earlier E-2 aircraft but added the digital Advanced Radar-Processing Subsystem (ARPS) that coaxes targets out of clutter.
The APS-138 has an improved overland/water capability through a Randtron Total Radiation Aperture Control Antenna (TRAC-A) that features low sidelobes. Using a Loral array track processor, the aircraft can simultaneously track more than 600 air targets and control up to 40 interceptions.
The APS-139, which was fitted to E-2Cs delivered from 1988 on, has an upgraded processor that allows tracking of more than 2,000 targets. In addition, the system has better Electronic Counter-Countermeasures (ECCM).
The rotodome revolves freely in the air-stream at the rate of 6 rpm. It provides sufficient lift to offset its own weight in
flight and can be lowered to facilitate handling the aircraft aboard ship. To make the most effective use of the radar, the E-2 cruises with a 10° flap setting, which gives the rotodome the desired 3° of incidence for scanning.
achieved initial operational capability in
1976, followed by the APS-138 in 1983 and the APS-139 in 1988. Manufactured
by General Electric in Utica, New York. Four Customs Service P-3 anti-drug-smuggling surveillance aircraft use APS-138 systems.
BAND B/C (UHF)
RANGE 250 nm (288 mi; 463 km)
NUMBER OF TARGETS more than 300
This search radar was built for use on the
41 US Coast Guard HU-25A Guardian surveillance aircraft; it also equips some aircraft in the Netherlands Air Force. It can be used in all weather conditions for search-and-rescue efforts as well as drug interdiction missions and enforcement of laws and treaties.
The APS-127 resembles the AN/ APS-124 used on the SH-60B in that it has a lightweight, fast-scanning planar-array antenna, with scan-to-scan integration and direct-view displays for the pilot and surveillance system operator.
Achieved initial operational capability in 1982; produced until 1984. Manufactured by Texas Instruments, Fort Worth, Texas.
RANGE AGAINST 10.8 FT2 (1 M2) TARGET 18 nm (20.7 mi; 33.3 km) PEAK POWER 200 kW
PULSE WIDTH 0.5 or 2.0 microsec PRF 1,600 or 400 Hz
SYSTEM WEIGHT 295 lb (134 kg)
ANTENNA BEAMWIDTH 5° X 6° ANTENNA DIMENSIONS
width 2 ft (0.62 m)
height 2 ft 6 in (0.76 m)
The AN/APS-133(V) is one of the most widely used color weather radars in US military service. Based on the commercial RDR-1F radar, the APS-133(V) is fitted to most US Air Force transports as well as several Marine Corps aircraft.
The stabilized parabolic antenna can emit either a pencil or fan beam and has varying scan angle. In the Type 2, the sector scan control panel allows adjustment of the scan angle from 15° to 75° to each side of the centerline, and the cen-terline can vary up to 75° to the right or left of the aircraft’s longitudinal axis.
The receiver/transmitter uses a solid-state modulator that transmits on three different pulse widths depending on its mode and has two Pulse Repetition Frequencies (PRFs).
First entered military service as part of C-141B upgrade in the 1970s. Installed on C-5, C-18, C-130, E-3, E-4, E-6, KC-10, and VC-25 (Air Force One) aircraft. The US Marine Corps introduced the later Type 2 in its aircraft in
BAND I (9.375 GHz)
TRANSMIT POWER 65 kW
weather: 300 nm (345 mi; 556 km) mapping or beacon: more than 250
nm (288 mi; 463 km) skin painting/air-to-air: 30 nm (34.5
mi; 55.6 km) PRF 200 or 800 Hz
PULSE WIDTH 0.4, 2-35, or 5.0 rmcrosec SYSTEM WEIGHT 104.4 lb (46.4 kg) ANTENNA BEAM WIDTH 2.9° (30-in antenna), 4.4° (22-in antenna)
ANTENNA SCAN RATE 45°/SCC
The AN/APS-134 is a coherent, pulse
Doppler Antisubmarine Warfare (ASW) search radar derived from the AN/ APS-116 radar for international sales. It is designed to detect submarine periscopes and antennas in rough seas. The system’s scanner is mounted in a nose radome, and the radar is integrated with the aircraft’s data systems.
In its periscope-detection mode in high sea states, the radar uses high peak power of 500 kW, high scan rates (150 rpm) with scan-to-scan processing for high resolution, short pulse widths, high Pulse Repetition Frequencies (PRF), pulse compression, and Moving Target Indicator (MTI) processing. Resolution is 1.5 ft (0.46m).
For navigation and surface search, the operator can select a high scan rate, high PRF, and pulse compression for high resolution of maritime targets; Track-While-Scan (TWS) is also available. A relatively slow scan rate, low PRF, and frequency agility are used for long-range search and navigation. The system can also apply Inverse Synthetic Aperture Radar (ISAR) processing to identify surface-ship targets.
The antenna is a vertically polarized, heart-shaped parabolic dish with feed horn and pressurized waveguide.
In production; manufactured by Texas Instruments. Fitted in updated New Zealand P-3B Orion, German Atlantic, and US Coast Guard HC-130 aircraft as well as new Pakistani P-3Cs.
WEIGHT 522 lb (237 kg) BAND I (9.5-10 GHz)
Peak 500 kW
average 500 W
long-range, high-resolution or surveillance 500 Hz
ANTENNA BEAMWIDTH 2.4° X 4° SCAN RATE
navigation/surface search 40 rpm
long-range search and navigation 6 rpm
The APS-144 is one of the sensors developed for the US Army’s Airborne Reconnaissance Low/ARL (formerly Grisly Hunter) program. ARL is being deployed in converted DHC-7 transports to aid in border surveillance. The small, low-power pulse-Doppler APS-144 should be able to detect small, slow-moving targets from the air. The usual benchmark is given as “a man leading a pack animal.” The radar was tested under the chin of a UH-60 helicopter, in a DHC-6 Twin Otter transport, and on board an Amber Unmanned Air Vehicle (UAV). Early versions had a 15.7-in (0.45-m) diameter antenna and an 8.1-nm (9.3-mi; 15-km) range.
First trials began in the late 1980s. Flight tests with the UH-60 occurred in 1991. Deployment of the ARL began in 1995-96. In production by AIL Systems.
WEIGHT less than 100 Ib (45 kg) DIAMETER 2 ft S’/a in (0.7 m) SEARCH RANGE 10.8 nm (12.4 mi; 20 km)
RESOLUTION BSf “SPOTLIGHT” MODE 50
ft (15 m)
The AN/APS-145 is an upgraded version of the AN/APS-125 surveillance radar fitted in US-built E-2C Hawkeye Airborne Early Warning (AEW) aircraft. It is likely to be the last of the series, with later shipboard AEW aircraft mounting conformal, or fixed, phased-array antennas.
The APS-145 introduced a lower Pulse Repetition Frequency (PRF) and ro-todome rotation rate to extend the radar’s range. Improvements in processing capability offset the coarsened velocity resolution that results from the lower PRF and rotation rate.
It also features “environmental processing” to screen out ground clutter. The search area is broken down into cells, each of which is assessed for clutter and target density. Sensitivity to clutter (both natural and man-made) can be adjusted by cell, which refines the system’s Electronic Counter-Countermeasures (ECCM). Automatic scan-to-scan checking of the 10 available transmission channels avoids jamming.
The rotodome revolves freely in the air-stream at the rate of 5 rpm.
Initial operational capability was achieved in 1991. Manufactured by Lockheed Martin Electronics Division, Utica, New York.
RANGE 350 nm (400 mi; 644 km)
The APY-1 is the primary radar for the E-3A Airborne Warning and Control System (AWACS) aircraft.
The AWACS antenna is mechanically scanned in azimuth and electronically scanned in elevation. While in flight, but not in operation, the saucer- shaped, 30-ft
(9.14-m) diameter rotodome rotates at 1A rpm to lubricate the bearings. Rotation speed climbs to 6 rpm during operation. The antenna is electronically scanned in elevation.
Most operational AWACS aircraft use an IBM CC-2 computer with a 665,360-word memory that is three times as fast as the earlier CC-1. Operating in the F-band, the radar uses pulse and pulse-Doppler modes as well as a high Pulse Repetition Frequency (PRF) for better look-down performance and higher resolution of targets with small Radar Cross Sections (RCS). The system can choose among several pulse widths depending on mode, and the antenna has low side-lobes, which reduces its sensitivity tojam-ming. Moveover, the radar’s azimuthal scan can be broken into 24 sectors, some ofwhich can be “blanked” (not scanned) to permit more detailed processing of other sectors.
Under the Radar System Improvement Program (RSIP), the system receives a new CC-2E system computer, new programming, a new surveillance radar computer, pulse compression, and the use of Fast Fourier Transform (FFT) processing to extract targets.
Development began in 1962, with the brassboard version entering test in 1971. Production began in 1975, and the first version achieved initial operational capability in 1978.
BAND F MAX RANGE
bomber: 300 nm (345 mi; 556 km) fighter with 75.3-ft2 (7-m2) radar cross section: 200 nm (230 mi; 370 km)
The AN/AWG-9 is the F-14 Tomcat’s
weapons control system that can simultaneously track up to 24 targets and guide missiles to six of them. Developed to control the AIM-54 Phoenix air-to-air missile, the AWG-9 can be used with AIM-7 Sparrow, AIM-9 Sidewinder, and AIM-120 AMRAAM, as well as for the F-14′s M61 20-mm Catling gun.
Although the AWG-9 has an impressive potential for fleet defense, the Phoenix has never been used in combat, and the F-14′s success rate with Sparrows against hostile targets in the 1980s (four Libyan and one Iranian aircraft) was one out of six. In fact, three of four Libyan aircraft shot down by F-14s were hit by IR-guided Sidewinders at close range.
The slotted planar-array antenna has a 36-in (914-mm) diameter and two rows of six dipole arrays for the Identification Friend or Foe (IFF) system. It is raster-scanned in “bars.” The AWG-9 radar can detect targets as low as 50 ft (15 m) and as high as 80,000 ft (24,384 m) at ranges over 115 nm (132 mi; 213 km), and across a front more than 150 nm (173 mi; 278 km) wide.
Its Traveling Wave Tube (TWT) transmitters can generate Continuous Wave (CW), pulse, and pulse-Doppler beams. One TWT provides CW illumination of a target for the Sparrow’s Semiactive Radar (SAR) homing seeker. The other TWT provides either conventional pulse or pulse-Doppler beams and can operate in one of several modes.
Pulse modes include Search (PS) and
Single-Target Track (PSTT). Pulse
Doppler modes include Search (PDS) for range rate and bearing, Range-While-Scan (RWS) that generates a range as well as range rate and bearing, Single-Target Track (PDSTT), and Track-While-Scan (TWS) for Phoenix missile targeting of up to 24 targets simultaneously. Time-sharing techniques permit simultaneous midcourse guidance of six Phoenixes at once against six different targets.
Other modes include a Vertical Scan Lock-on (VSL) with a lower threshold between 15° below the aircraft axis (ending at 25° above) and 15° above (ending at 55° above). Pilot Rapid Location (PRL) is effectively a boresight mode using a 2.3°-wide beam.
Both conventional and pulse-Doppler modes can be slaved to an Infrared Search and Tracking (IRST) system in which the IRST passively acquires a target and the radar illuminates the target at the appropriate time.
Development began in the mid-1960s as part of the abortive F-111B fleet defense aircraft program. Production of complete AWG-9 systems began in the early 1970s and ended in August 1988; spares manufacture ended in 1989. Manufactured by Hughes Aircraft Co. Radar Systems Group, El Segundo, California.