The Bars is a family of Russian all-weather multimode airborne radars developed by the Tikhomirov Scientific Research Institute of Instrument Design for multi-role combat aircraft such as the Su-27 and the MiG-29.
The BARS was developed by the Russian industry during the 1980s. It is unusual in being designed with a hybrid array arrangement, the receive path using very similar technology to the Western radar, with similar sensitivity and sidelobe performance, but using a Travelling Wave Tube and backplane waveguide feed for the transmit direction, a technology closest to the B-1B and early Mirage radars. As such the BARS is a transitional design envisioned in between Passive ESAs (PESA) and contemporary Active ESAs but during the production phase, Russia stick to the pulse doppler phased array radar design.
There is no doubt this design strategy reflected the unavailability to Russian designers of the Gallium Arsenide power transistors used in Western AESAs. The design was a stopgap Russian radar before Russia could actually develop an AESA radar which Russia never materialized.
The baseline N011M radar uses a vertically polarised 0.9-metre diameter aperture hybrid phased array, with individual per element receive path low noise amplifiers delivering a noise figure cited at 3 dB. The antenna is constructed using phase shifter and receiver ‘stick’ modules, a similar technology to the early 1970s.
Three receiver channels are used, one presumably for sidelobe blanking and ECCM. The EGSP-6A transmitter uses a single Chelnok Travelling Wave Tube, available in variants with peak power ratings between 4 and 7 kiloWatts, and CW illumination at 1 kW. Cited detection range for a closing target (High PRF) is up to 76 NMI, for a receding target up to 50 NMI. The phased array can electronically steer the mainlobe through +/-70 degrees in azimuth and +/-40 degrees in elevation. The whole array can be further steered mechanically. Polarisation can be switched by 90 degrees for surface search modes.
The BARS remains in production for the Indian and Malaysian Irkut built Su-30MKI/MKM variants. The radar is available with a range of TWT power ratings, this being the source of considerable confusion to observers who have not tracked this program since its inception. The result is a wide range of performance figures depending on the resulting Power Aperture Product. That the antenna has not gained power handling capability is evident in its adaptation for the Irbis E design.
Given the similarity between the Irbis E and BARS, existing BARS operators will over time effect block upgrades to convert their BARS inventories into the Irbis E configuration, but considering both the technology gained during 1970s the actual technology is three decades behind any modern western radar.
The first Bars series radar was the N011, which was originally an X band Pulse-Doppler radar developed for the Su-27. In this original N011 form, it deployed a mechanically scanned planar array with 960 mm diameter, ±85 degrees scan sector. The peak output power reached 8 kW with an average of 2 kW. The N011 features a low noise UHF input amplifier, and fully digitized signal processing unit using reprogrammable digital computers.
The original requirement to simultaneously track 20 targets and engage 8 of the 20 tracked proved impossible to achieve at the time due to the available Soviet technology, but the N011 is still able to simultaneously track 13 targets and engage 4. This was subsequently upgraded to tracking 15 targets and engaging 6 of the 15 tracked. The maximum air-to-air detection range is over 400 km when used in an airborne early warning role, and when used for intercepting role, the range against a typical fighter sized target is 140 km head-on, and 65 km tail-on.
For air-to-surface mode, the N011 has five air-to-ground modes and four maritime modes, including ground mapping, terrain-following radar and terrain avoidance modes. The maximum air-to-surface mode is over 200 km against an aircraft carrier type of target.
The second member of the Bars radar family is the N011M, a radar that uses an electronically scanned phased array slotted planar antenna but with the experience gained from the development of the N007 Zaslon. In an effort to improve performance the antenna design was changed to a multi-channel passive electronically scanned array PESA. The design of the N011M Bars antenna like the earlier N007 antenna consists of two separate electronically controlled arrays, an X band radar and an L band IFF transponder with a total weight of 100 kg and a diameter of 960 mm. The radar has a peak power output of 4-5 kW and is capable of positioning beams in 400 microseconds, a huge advantage over mechanically scanned radar. The Bars radar can be fixed in position to give a scanning sector of ±70 degrees in azimuth and ±45 degrees in elevation. To improve scan coverage, the radar can also be mounted on electromechanical drives, and in this case, the scanning sector is expanded to ±90 degrees.
The 28 MHz Ts200 programmable signal processor used in N011M incorporates Fourier transforms of “butterfly” type capable of 75 Million operations per second. The N011M supports digital signal processing using 3 processors with 16 MB of both static and flash memory. The peak output is 4 to 5 kW with an average output of 1.2 kW, and the total radar system weighs around 650 kg. N011M is used on Su-30MKI, and the contract for the N011M radar has three stages. The initial MK1 software was tested in 2002 and supplied with the first Su-30MKI deliveries. India was supposed to build both programmable signal processors and data processors under project “Vetrivale” to replace the original Russian components, but failed to do so within the required time frame, so MK2 still used the Russian equipment. In 2004, India delivered Vetrivale radar computer based in the i960 architecture. Its worth noting that N011M is not simply a PESA, but instead, its a transition between PESA and AESA in that it adopts technologies from both: each transceiver on the antenna array of N011M has its own receiver amplifier, which is the same as AESA, and with noise level of 3dB, which is also in the same class of AESA arrays. However, for transmitting, N011M uses PESA technology in that a single Chelnok traveling-wave tube is used for EGSP-6A transmitter. There are three receiving channels for N011M.
N011M has a search range of 300 km and a tracking range of 170 km, with 60 km in the rear in the air-to-air mode. Detection range fighter-type MIG-29 in area of review of over 300 sq. deg: – on towards course – up to 90 km; – in pursuit of – up to 60 km. Up to 15 air targets can be tracked at once in track while scan mode with 4 of these engaged at once. The N011M can use a number of short-range and speed search modes and is capable of identifying the type and number of multiple targets. The Bars radar is compatible with R-77 and R-27 radar-guided missiles providing both illumination and data-link guidance as well as the R-73 IR guided missile.
In the air-to-surface mode the radar is capable of detecting ground and naval-based moving targets, determining their location and maintaining a track on two surface targets at once. The N011 is capable of detecting the group of tanks target to a maximum range of 40–50 km and a destroyer sized target to a range of 90 km. Bars also features a mapping mode using either real beam, Doppler beam sharpening or Synthetic aperture radar with a maximum resolution of 10 meters. The Kh-31 anti-radiation missile is also compatible with the radar.
N035 Irbis-E Snow Leopard radar is the most powerful radar of Bars radar family, and it is a direct descendant of N011M, and it adopts many components of N011M to save cost and shorten the developmental time. The difference between N035 and its predecessor N011M is that the receiving channel is increased to 4 in N035 from the original 3 in N011M. A new transmitter EGSP-27 incorporated an upgraded version of Chelnok traveling wave tube that is capable of delivering 10 kW peak power output, resulting in the peak output of N035 increased to 20 kW, with an average output peak of 5 kW and continuous wave illumination of 2 kW. A new 5010-35.01 digital processor and a new 5010-35.02 info processor are used, and N035 has twice the bandwidth of N011M.
The noise level is increased to 3.5 dB from the 3 dB of N011M, and against typical aerial target with 3 square meters, the effective range is in excess of 300 km head-on. Against target with 5 square meters, the head-on effective range is in excess of 90 km. N035 radar can simultaneously tracking 30 targets and engage 2 of the 30 with semi-active radar homing air-to-air missiles, and when using active radar homing missiles, the number of targets it can simultaneously engage is increased to 8.
The Tikhomirov Scientific Research Institute of Instrument Design has displayed a modified N011M radar for the MiG-29 designated the Bars-29. The Bars-29 shares up to 90% of its software and hardware with the original Bars radar while being small enough to be installed within the nose of the MiG-29 fighter. The Bars-29 has a detection range of 90km km against a target with an RCS of 5 sqm , 15 targets can be tracked at once when using track while scan mode, with 4 engaged at any one time. The radar has an average power output of 1 kW.
Limitation of BARS
The passive phased array system operates on X and L band (NATO D & I bands). The tracking performance mentioned is also way too low. The original SU-27M/SU-35 could track 15 targets, and track-while-scan 8 targets. It could engage 6 targets simultaneously. The N011M radar has limited capability in terms of SAR modes.
The 90KM detection range would apply to fighter-sized targets in the class of an F-16. The range was reportedly 80-100KM for an RCS of 5 sqm, and up to 300KM for RCS of 20 sqm jump jets size target. A SU-27 fighter can reportedly detect jumbo jets at a range of over 300KM with a variant of the radar.
The performance of the TZ-100 computer on the MIG-29 Fulcrum A’s N-019E radar was rated at just 250,000 operations per second. The radar’s MTBF is also tenth time lower than any western radars. The most of Russian fire control radars are derivatives of 1970s and 1980s technology. Phazotron are claiming Zhuk-ME has a much faster signal processor than the N011M.
This is why the BARS radar’s SAR resolution is restricted. The Ts200 is a first-generation PSP developed in the late 80s USSR for the N011 radar. In Phazotron’s terms its like the PSP of the original “Zhuk”. Phazotron now uses a new design PSP with western processors for “Zhuk-M” and “Kopyo-M”, which is notably faster and hence able to give better resolution. Russia offered Sokol radars for China for the J-10 as the “Zhuk-10PD” which is developed into KLJ-7A radar. One of the reasons, China opt-in for Zhuk-10PD is that Zhuk-10PD is a cheaper array design seen in Zhuk-MSF/Sokol radars.
The IAF evaluated the Phazatron/NIIP offerings, the computing is still lagging behind the Western counterpart. Today, with western microprocessors being imported, speeds of 900 million operations per second have been reported. Russian radars still lag way behind the latest western offerings for their new generation fighter radars such as Su-57 and Su-35 radars.
The N-011M ranging from 4 targets all the way to 8 targets. The N-011 (the conventional variant) found on the SU-35 engages 6 targets at once.
The BARS radar was solely responsible for the failure of the Indian Air Force in Kashmir skirmish, Indian Air Force’s R-77 missile failed to lock on the Pakistan Air Force’s F-16 because BARS radar mostly incapable of locking on target when travelling more than MACH 1 speed whilst in pursuit with adversary fighters. The Pakistan Air Force’s F-16C could track Su-30MKI from 150km distance and lock on target within the range of 120km, the Indian Air Force could track Pakistani F-16 within 90km range which means Pakistani F-16 has seen Su-30MKI first and launch AIM-120 AMRAAM first and Indian Air Force has to wait for Pakistani F-16 to be tracked within the BARS radar detection range of 90km and engagement range of R-77 of 70km.
© 2021, GDC. © GDC and www.globaldefensecorp.com. Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to www.globaldefensecorp.com with appropriate and specific direction to the original content.