The primary sensor of the modern fighter remains the radar. Up until the 1980s operating a radar effectively required a great degree of skill; today’s digital radars are simple to use, long-ranged and harder to jam than ever. As well as detection, modern sets can be used to jam, communicate and collect information about enemy sensors and communications. In the future AESAs will even be able to ‘fry’ enemy radars by overloading them with radio energy. That aircraft like the Rafale and Super Hornet are equally adept at the air superiority and ground attack missions has a great deal to do with the extreme versatility of the contemporary radar, which can simultaneously scan the air for fighters as it looks for ground targets. There are two types of fighter radar, mechanical- and electronically scanning. The latter can be divided into three categories: passive scanning, active scanning and ‘hybrid tilters’. The passive electronically scanning array radar (PESA) have a single radio source that sends energy to multiple receive/transmit modules. The PESA is relatively simple to create, but not as versatile as the AESA. The first PESA fighter radar was carried by the MiG-31, which entered service in 1981. The active electronically scanned array (AESA) also uses multiple modules but each can send a different radio signal (different in frequency or direction) allowing a greater degree of versatility, and making the radar harder to jam. The first frontline fighter to carry an AESA was the Mitsubishi F-2, though the Raytheon APG-63(V)2 for the US’ F-15C beat the type into full operational service in 2000. One of the limitations of AESA in the fighter role is that the signal is weaker at extreme fields of regard – a AESA can only see well at up to 60 degrees to the side. This issue will be addressed in the new hybrid tilting radars for the Typhoon and Gripen E/F which are AESAs mounted on tiltable plates. Russia’s PAK FA will also address the ‘field of regard’ issue with cheek-mounted arrays (additional to the AESA in the nose). However- neither the new Gripen E/F, Typhoon or PAK FA radar have entered service so do not make this list.

Radar performance is an extremely sensitive subject with security implications, so most of the important data is classified- but a broad understanding of capabilities can be described from open sources. The order is meaningful, but certainly not definitive: adhering to the top 10 format always requires a simplification. Much is open to interpretation so I am happy to receive corrections and additional information from reputable sources. 

Saab has made dramatic claims about improvements to the PS-05’s performance. The most advanced version in service is the Mk 3. (Graphic from Saab)

9.NIIP N011M Bars and RP-31M Zaslon

The BARS is unusual in being designed with a hybrid array arrangement, sitting between Passive ESAs (PESA) and contemporary AESAs. This design solution may have come from the absence of the notoriously tricky to master Gallium Arsenide power transistors (even Western European companies, with their greater emphasis on high technology, found this hard).

Design maximum search range for an F-16 target was said to be 140-160km, and an early lower-power version is said to have detected a Su-27 at over 320km. It is carried by all Su-30M and until recently was the best radar in service on a Russian fighter. The enormous power is a mixed blessing: it endows it with an impressive detection range, but also makes it detectable to hostile sensors from huge distances.

RP-31M

The MiG-31’s RP-31 was the first ever operational electronically-scanned phased array fighter radar. The M variant can track up to 24 targets and simultaneously engage four well-spaced targets flying at altitude 50 m to 30 km and with a speed of 3,700 km/h (head-on). Claimed search ranges for the earlier variants are 280 km for the E-3 Sentry, 200 km for SR-71 flying at over 25 km altitude, 180 km for B-1B, 120 km for F-16 and 65 km for low-flying AGM-86B cruise missiles, all head-on (tail-on ranges are about 40-50% of the above). Search angles are 70° each side in azimuth, and +70°, -60° in elevation. The RP-31M has even greater search ranges- in 1994 it was claimed that a MiG-31 destroyed a target 300km away using the R-33 missile.

Photo credit: Jamie Hunter/Eurofighter

8. Euroradar Captor The Last Swinging Disc in Town and RP-31 Zaslon-A pulse-Doppler radar

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That Typhoon still does not have an AESA, is something of an embarrassment to Eurofighter, who could be said to fudge the facts in their literature to imply that Captor-E is in service: it is not. But at least the existing Captor-M is the best mechanically-scanning radar in the world, with twice the power output of the APG-65, the ability to track 20 air targets simultaneously and automatically identify and prioritise them. It is a coherent I / J-band (8-12 GHz) pulse Doppler, radar with a 70cm diameter antenna. Even though it features a mechanically steered array, the low inertia non-counterbalanced antenna combined with four high torque, samarium-cobalt drive motors is capable of extremely high scanning speeds. The most remarkable achievement for the Captor is its ability to interleave different operations (such as air and ground mapping), something few if any other mechanically scanning radars can match to the same degree. It is unique in having a separate data channel exclusively for screening ECM, claiming to offer a robust protection from enemy interference (though a mechanical radar is still more vulnerable to jamming than an AESA set). Released figures state that the Captor can detect MiG-29-sized targets at 160 km and C-160s at over 320 km. The electronically scanned Captor-E that will probably replace the Captor is expected to be an exceptional device, in some respects (field of regard and possibly range) superior to even the F-22’s APG-77. Eurofighter have commented that during evaluations by potential customers looking at Typhoon and Rafale, that Typhoon consistently detected targets at longer ranges than did the PESA RBE2. In the Swiss evaluation (below) Typhoon scored worse than Rafale for acquisition but better for engagement.

An evaluation of the Typhoon versus the Su-35, can be found here.

7. N135 Irbis

The Su-35 is now in operational service with the Russian air force and according to some analysts is an effective counter to Europe’s Typhoon and Rafale. The primary sensor of its integrated suite is the monstrously powerful N135 Irbis, a passively scanning electronic array radar (in some respects a PESA/mechanically scanning hybrid). Compared to the Bars radar of earlier ‘Flanker’s it has a wider range of operational frequencies, greater angular search zone of up to +/-125° (due to better aerial and double-step drive), longer range and better resistance to jamming and finer resolution. It offers ‘track while scan’ (a mode where the radar allocates part of its power to tracking a target or targets while still scanning for more) for up to 30 air targets, eight of which can be simultaneously engaged them by active-radar AAMs. At peak power  (limited to narrow sector) it can see a fighter-sized target from 217-249 miles (350-400 km) in head-on or 93 miles (150 km) in tail-on position.

6. Raytheon AN/APG-79 (Super Hornet) The Unreliable Witness of the Fleet 

The Super Hornet‘s AESA radar, with 1100 (it may actually be as high as 1368)  transmitter/receiver modules, is very impressive on paper, but reports from the Director, Operational Test and Evaluation (DOT&E) indicated less than glowing reviews from the real world: a 2007 report assessed it as not operationally effective or suitable due to significant deficiencies in tactical performance, reliability, and built-in test (BIT) functionality. The US Navy conducted an APG-79 radar follow-on test and evaluation in 2009 and reported that significant deficiencies remained for both APG-79 AESA performance and suitability; DOT&E concurred with this assessment. Since then there have been some improvements however, “operational testing does not demonstrate a statistically significant difference in mission accomplishment between F/A-18E/F aircraft equipped with AESA and those equipped with the legacy radar“. A report released in 2013 cited ‘The radar’s failure to meet reliability requirements and poor BIT performance remain as shortfalls from previous test and evaluation periods‘. Despite this, many pilots have expressed delight with the abilities of the radar, especially its power to perform two tasks (A2A + A2G) at once. In 2015 Raytheon has flight tested the APG-79(V) X, a scaled down version intended for the legacy (C/D) Hornet fleet.

THALES / Ecrans du cockpit du Rafale, à Dassault Aviation (HM1) sur la base aérienne d’Istres, le 11/12/2008.

5. Thales RBE2 AESA

Though the AESA variant of the RBE2 may be one of the smallest radars on this list it should not be underestimated. When the Rafale entered service in 2001 it carried the RBE 2 radar, the first electronically scanning fighter radar in Western Europe. The radar has greatly impressed pilots, with many commenting on the excellent situational awareness it provides, and how easy it is to use on combat missions. The original RBE 2 is a passively scanned radar (the first of this type was the MiG-31’s Zaslon of 1981), something many consider a technological cul-de-sac. PESA’s have a single critical failure point, a risky proposition in a combat radar. But the PESA was a stepping stone to AESA development. It was a huge publicity coup for Thales, when the RBE 2 AESA became the first European AESA radar to enter operational service. The AESA has a field of regard of 70° on either side of the aircraft axis and between 800-1100 T/R modules. According to Thales, the radar offers an impressive improvement over the earlier passive-scanned RBE 2; in terms of performance, detection range is increased by more than fifty per cent and the radar’s ability to ‘look’ in many directions simultaneously offers enhanced tracking capabilities. Angular coverage in azimuth is improved and targets with lower radar cross section can also be detected. While understandably cagey in discussing such a sensitive subject, Thales acknowledges multiple Rafales with AESA could work together to detect stealthy targets. It is expected that electronic attack capabilities will be impressive and work hand-in-hand with the widely respected SPECTRA suite, though Thales also refuses to comment on this sensitive subject. Unlike the Raven and Captor E, the RBE 2 AESA is a conventional fixed AESA. The decision not to include a repositioner was made in the mid-1990s after a detailed study. The conclusion was drawn that though a repositioner is a good solution when the combat situation is simple, it becomes absolutely irrelevant when the battlespace becomes more complex, due to a high quantity of targets spread in space. The repositioned solution was also considered irrelevant for the majority of the missions. Cynical observers have questioned whether a repositioner could have been fitted in the petite nose of the Rafale, though the success of the Gripen’s Raven suggests this need not be an issue. Converting a Rafale to the new radar is reportedly very easy: it takes less than two hours to remove the PESA and to ‘plug and play’ the AESA antenna. The RBE 2 AESA is the same weight as the baseline radar and uses the same interface. Sixty RBE 2 AESA were ordered for Batch 4 Rafales; there are currently no plans to reequip the rest of the air force and navy fleet.

4. AN/APG-80

The F-16E/Fs radar was said to be the first example of export customers receiving superior kit to USAF. It has a higher reliability and twice the range of older, mechanically-scanned AN/APG-68 radar systems. It has around 1000 T/R Modules and is considered by pilots both reliable and mature (think George Clooney).

3. Raytheon AN/APG-63(V)3 (F-15C/F-15SG)

Building on the experience with the APG-79 but with the capacious nosecone and huge electrical power of the F-15 allowed Raytheon to create a radar that is both sophisticated and extremely powerful. The APG-63 has come on leaps and bounds from the rather primitive and ineffective set fitted to the original F-15As – in fact the new radar features little of the original mechanical set. Raytheon is the most experienced manufacturer and designer of AESA radars in the world- the company dominates the AESA market, according to the company’s promotional material it has produced 500 of the 780 AESAs in service worldwide – and the creation of an active ’63 has given the old Eagle a formidable improvement. The APG-63(V)3 radar is an update of the (V)2of the APG-63(V)2, applying the same AESA technology utilised in Raytheon’s APG-79. The (V)3 is designed for retrofit into F-15C/D and deployed in Singapore’s new F-15SG aircraft. Those F-15s fitted with the V3 are a match for any potential adversary in the beyond-visual-range fight.

2. Northrop Grumman AN/APG-81 Eye of the blighted Though the F-35 has endured a horrific development, one success story from this blighted programme is the radar which is by most accounts excellent. It is likely that its offensive jamming capabilities (using the AESA) will be a significant development in the history of aircraft radar. The complexity of the F-35 sensor and weapon system is such that the potential (and an acceptable level of reliability) is unlikely to be reached for some years. Much of the F-35’s unprecedented level of situational awareness is thanks to the highly automated and extremely sophisticated ’81.

Type: AESA T/R Modules 1200

1. Northrop Grumman APG-77(V)1 American Sniper No expense was spared in creating the F-22‘s main sensor. Large, powerful and sophisticated, the APG-77 is also beneficiary to almost unlimited funding to keep it at the top of its game. The APG-77 is an active electronically scanning radar and has an impressive 1500 transmitter receiver modules. The relationship between performance and the amount of T/R modules is such that manufacturers are very cagey about sharing specifics (though observers with obsessive tenacity can count the amount visible from photographs). One disadvantage of the ’77 its is use of old-fashioned CPUs, which are tricky to maintain.The degree of sensor fusion in the F-22 is very high- in particular the relationship between the F-22’s radar and EW suite, further enhances the APG-77’s effectiveness. One of the main advantages of this radar is the Low Probability of Intercept (it is designed to not be conspicuous to enemy radar warning receivers), if this works in combat it will be a major boon. Some wonder the degree to which modern AESA-based RWRs would be able to detect it even a LPI radar, but international training exercises show that LPI does work, with feckless opponents having little warning of an impending Raptor attack.

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Have a look at 10 worst British military aircraft, Su-35 versus Typhoon, 10 Best fighters of World War II , top WVR and BVR fighters of today, an interview with a Super Hornet pilot and a Pacifist’s Guide to Warplanes. Was the Spitfire overrated? Want something more bizarre? The Top Ten fictional aircraft is a fascinating read, as is The Strange Story and The Planet Satellite. The Fashion Versus Aircraft Camo is also a real cracker. Those interested in the Cold Way should read A pilot’s guide to flying and fighting in the Lightning. Those feeling less belligerent may enjoy A pilot’s farewell to the Airbus A340. Looking for something more humorous? Have a look at this F-35 satire and ‘Werner Herzog’s Guide to pusher bi-planes or the Ten most boring aircraft. In the mood for something more offensive? Try the NSFW 10 best looking American airplanes, or the same but for Canadians.

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