The Su-35’s Irbis-E radar combines passive PESA scanning, a declared range of 400 km, LPI modes, and R-37M missiles to counter stealth. Technical analysis.
Summary
The Su-35 equipped with the N035 Irbis-E radar has an advanced detection system based on PESA (Passive Electronically Scanned Array) architecture. Although this technology predates AESA radars, it can achieve declared ranges of around 350 to 400 km against targets with a conventional radar cross section (~3 m²) and around 90 km against very low-stealth targets (e.g., RCS ~0.01 m²). The radar can track up to 30 air targets simultaneously and engage up to 8 of these targets at the same time. It is also coupled with L-band radars (N036B-1-01) to extend coverage against stealth signatures. Thanks to “low probability of intercept” (LPI) modes, the aircraft can limit its radar emissions and launch long-range missiles such as the R-37M (Mach 6, ~300 km+) without being detected. This combination challenges part of the “inviolable stealth” doctrine by forcing the adversary to consider visual combat, an area in which the Su-35 excels thanks to its super-maneuverability.
The context of the Su-35 aircraft and its radar
The Su-35 is the “4++ generation” evolution of the Russian Su-27 fighter. It is powered by two AL-41F1S turbofan engines, features thrust vectoring control surfaces, and incorporates a modernized avionics suite. According to public data, it has a wingspan of approximately 15.3 m, a length of approximately 21.9 m, and an operational ceiling of approximately 18,000 m.
The Irbis-E radar was developed by the Tikhomirov NIIP institute based on the Bars (N011M) radar used in the earlier Su-30 and Su-35 aircraft.
It is a central component of the aircraft’s fire control system, giving it all-terrain and all-speed acquisition and tracking capabilities. This radar architecture is one of the key selling points for the Su-35 (e.g., China, Algeria, etc.).
The requirement was to equip a non-stealth aircraft with a sensor capable of “seeing far,” detecting targets at long range, and thus compensating for its lack of stealth. The choice of a powerful PESA (with mechanical antenna and active gallium arsenide modules) meets this requirement.
Technical characteristics of the Irbis-E radar
Detection range and anti-stealth capability
The manufacturer states that the radar can detect a target with a radar cross section (RCS) of approximately 3 m² at a range of up to 350-400 km in “narrow beam search” mode. Some sources moderate this to approximately 200-250 km in wide search or “uncued” mode.
For stealth targets with very low RCS (≈0.01 m²), independent estimates indicate ranges of 50-90 km or even less. One analyst cites 48 km of detection and 30 km of tracking for an F-35.
The radar claims the ability to track up to 30 targets simultaneously and engage up to 8.
Architecture and modules
The N035 uses a PESA antenna mounted on a two-stage electro-hydraulic drive, offering a mechanical field of view (azimuth ±60°) and electronic field of view (beam scanning ±60°) for a total advertised field of view of approximately ±120°. The transmit/receive modules are made of gallium arsenide (GaAs), which enables high performance in terms of transmit power and receive sensitivity.
Signal processing is provided by a Solo-35.01 unit and a Solo-35.02 data processor, inherited from the Bars radar but greatly improved.
Modes and spectral coverage
The radar offers air-to-air (detection/tracking) and air-to-ground (mapping, SAR, Doppler beam sharpening) modes. In air-to-ground mode, it can detect and engage up to four ground or naval targets while continuing to search the air.
The integration of complementary L-band radars (N036B-1-01 wing radars) extends frequency coverage and improves the detection of stealth signatures, as the L-band is less affected by certain stealth techniques.
LPI and radar stealth modes
The radar is designed to have Low Probability of Intercept (LPI) modes, reducing the amount and consistency of radar emissions in order to limit detection by enemy radar warning receivers. In this way, the aircraft can launch long-range missiles without being too easily detected. This feature is a claimed argument for anti-stealth warfare.
Radar/missile combination and tactical doctrine
The Su-35 with its Irbis-E can carry long-range missiles such as the R-37M (or RVV-BD), capable of reaching up to 300-400 km depending on the profile.
The tactical logic is as follows: detect an adversary (standard or stealth) at a distance, engage from a relatively safe position, possibly without revealing one’s own location thanks to LPI modes, then, if the adversary enters the visual zone, use the Su-35’s high maneuverability for close combat.
This approach partially contradicts Western doctrine based on stealth and BVR (beyond visual range). Indeed, Russian radar claims to be able to detect targets at very long range, forcing the opponent to rethink stealth superiority. Some analyses suggest that a Su-35 could detect an F-35 before the latter sees it, leading to combat not only at long range but also within visual range, where the Flanker excels.
Furthermore, the Irbis-E’s ability to remain in standby mode while monitoring airspace and guiding missiles while the aircraft performs other tasks makes it a versatile tactical tool.
The strengths and limitations of the Su-35’s PESA solution
Strengths
- The high level of transmission power allows for long detection ranges (350-400 km announced).
- The multi-target capability (30 tracks / 8 engagements) is advantageous in a complex air-to-air scenario.
- The integration of L-band coverage and LPI modes provides resilience against stealth and electronic countermeasures.
- The combined use of long-range missiles forces the adversary to redeploy its defenses and modify its doctrine.
Limitations
- The radar remains a PESA, whereas AESA (Active Electronically Scanned Array) radars offer superior advantages: better resistance to jamming, more advanced multi-function capabilities, and less vulnerability to emission detection.
- The advertised detection performance (400 km) is highly dependent on the target profile, its RCS, altitude, and azimuth, and is often valid in “cued” mode (with support from another radar or AWACS), which reduces the practical range in autonomous search.
- Against low RCS stealth targets, ranges drop sharply (50-90 km).
- The doctrine requires good intelligence, good threat management, and consistent tactics. Without this, the aircraft could find itself vulnerable.
- In some field reports (e.g., Egypt), integration or component defects have been reported, affecting the reliability of radar and engine systems.
The strategic and tactical implications of the Irbis-Su-35
Tactical paradigm shift
The fact that a non-stealth aircraft such as the Su-35 can claim long-range detection capabilities calls into question the absolute supremacy of stealth. The adversary must now anticipate that a “simple” Flanker equipped with a high-performance system can detect, track, and engage from a great distance. This requires changes in mission planning, in the use of stealth aircraft, and in threat management.
Increased pressure on the adversary
By forcing an adversary to redeploy its surface-to-air systems, engage interceptors, and protect remote sites, the Russian Air Force with the Su-35 can impose logistical and defensive attrition. The adversary must devote resources to defending large areas, not just around the front. This creates a multiplier effect.
Export positioning and geopolitical influence
The Su-35 is being offered to many countries, and the Irbis-E radar is a major selling point. Client states are sensitive to the ability to monitor large volumes of airspace. This influences regional balances, particularly when faced with forces equipped with stealth fighters.
Adaptation of counter-stealth
The integration of an L-band radar and LPI modes signals a different approach to counter-stealth. Instead of relying solely on passive stealth, the system relies on raw power and multi-band integration to detect stealth signatures.
Doctrine limitations and future
However, if the adversary has modern AESA radar, good electronic warfare capabilities, and numerically superior fighters, the situation could be reversed. The Su-35 remains vulnerable without network support, high-performance missiles, or quality intelligence. Finally, the transition to AESA radar is already being discussed for the Su-35SM version, which shows that even the Irbis-E architecture could become obsolete.
The Su-35’s Irbis-E radar is not a technological panacea, but it represents a pragmatic and powerful approach to long-range detection and engagement in the modern air environment. It demonstrates that a well-integrated aircraft-radar-missile combination can force an adversary to redefine its tactical priorities. At a time when stealth is regularly presented as the ultimate solution, Russia reminds us that there are other avenues, based on power, broadband coverage, and radar/missile integration. The equation for a Western aircraft is now: how long can it remain invisible, how much time does it have to gain, and can it apply a doctrine of air superiority if an adversary can potentially see it coming? The debate is open.
Live a unique fighter jet experience