Uttam AESA Radar. Uttam is a solid-state gallium arsenide (GaAs) based active electronically scanned array (AESA) radar under development by the Electronics and Radar Development Establishment (LRDE), a laboratory of the Indian Defence Research and Development Organisation (DRDO). It is a low probability of intercept radar. It is a liquid cooled AESA radar featuring quad band modules that can be stacked to form a larger unit. This allows the manufacturer to scale the radar to be used in larger aircraft.

Development 
The radar development began in 2012 and its full-scale model was displayed at the 2017 Aero India air show and aviation exhibition. A fully functional active electronically scanned array (AESA) radar prototype was unveiled at Aero India 2019, the prototype was mounted inside the glass nose of a HAL Tejas prototype. 

Hindustan Aeronautics Limited is the lead integrator and Bharat Electronics is major supplier of subsystems. As per Project director D Seshagiri of Electronics and Radar Development Establishment (LRDE), Uttam AESA radar is 95% indigenous, with only one imported subsystem. The National Flight Testing Centre had evaluated the radar and cleared it after performance tests. The integration problem of Astra BVRAAM due to older generation of radars will also be solved by Uttam.

During Aero India 2021, there was a licensing agreements for technology transfer from DRDO to Hindustan Aeronautics Limited for manufacturing and integration of the Uttam in the Mark 1A variant of the HAL Tejas.

Testing 
As of 2021, three units were in various phases of testing. The Uttam radar has completed 230 hours of airborne testing onboard two Tejas fighter jets (LSP2 and LSP3) and on an executive jet; presumed to be DRDO's Dornier 228 "Nabhratna" used as a flying test bed by LRDE. Once fully validated and certified, it is planned is to introduce the radar in later batches of Tejas Mark 1A aircraft. The Uttam radar will be used with DRDO's Unified Electronic Warfare suite. Indian Air Force Test Pilot School would start final demonstration trial of Uttam AESA radar from December 2021 and if successful will be sent for serial production. LRDE has completed 250 hours of performance testing on two Tejas fighters as well as Hawker 800 executive jet.

As of April 2024, the radar has completed 125 test sorties onboard Tejas Mk 1 prototypes as per ADA Director Dr Jitendra Jadhav. The radar has cleared testing Air to Air (A2A) and Air to Ground (A2G) modes while few more tests are yet to be conducted. The performance of the radar is on par with other proven designs like EL/M-2052.

Features

Full solid-state (electronics) radar, based on GaAs
High MTBCF (redundancy)
Range: >100 km
Multi Target Tracking (50 Targets), Priority Tracking (4 Targets).
Simultaneous operation modes.
Solid-state, active phased array technology
Pulse Doppler, all aspect, shoot down capabilities
Simultaneous multi-target tracking and engaging 
Simultaneous multi-mode operation
High ECM immunity
Ultra-low side-lobe antenna
Flexible interfaces allowing scalable design.
Modular hardware and software
Fast-beam agile system
Quad band TRM modules pack
High mission reliability (built with redundancy)
IFF modes.
 C-band LOS, Ku band satcom link.

Operational Modes 

Uttam AESA radar has a total of 18 modes in Air to Air, Air to Ground and Air to Sea roles. The modes have been validated on-board a business jet and further proofing is being done on HAL Tejas to validate the same on supersonic platform.
 
 Air-to-Air
 TWS/Multi-target detection and tracking
 Multi-target ACM
 High resolution raid assessment
 Air-to-Ground
 High resolution imaging (SAR Mode)
 High resolution tracking (SAR Mode)
 AGR – Air-to-Ground Ranging
 RBM – Real Beam Map
 DBS – Doppler Beam Sharpening
 GMTI on RBM, SAR
 Weather
 Air-to-Sea
 High resolution imaging (SAR Mode)
 High resolution tracking (SAR Mode)
 Sea search and multi-target tracking
 RS and ISAR classification modes.

Virupaakhsha 
Virupaaksha radar is an advanced version of the Uttam Mk-II radar. The radar under development will replace the current N011M Bars radar being used onboard the Sukhoi Su-30MKI after the Super Sukhoi upgrade program.

Virupaaksha utilises Gallium Nitride (GaN) technology with improved radar operational characteristics than Gallium Arsenide (GaAs) used by earlier variants. GaN provides better power output, enhanced thermal efficiency, wider bandwidth of operation, and a longer lifespan compared to earlier variants. The radar incorporates the quad transmit-receive modules (T/R modules) similar to Uttam but has a more densely packed configuration and has around 2400 modules based on GaN based planks. The plank configuration eases maintenance operations. Reportedly, the radar succeeded to track 64 to 100 aerial targets simultaneously during trials and offers at least 1.7 times increased head-on search range over the 140 km-range N011M Bars radar. It features advanced electronic counter-countermeasures (ECCM). The Virupaksha radar operates in the S-band frequency range, and can detect and track a wide range of targets like aircraft, helicopters, drones, and even ballistic missiles. It has a reported head-on search range of over 400 km, though the value is officially classified.

As of October 2024, LRDE plans to set up "assembly jigs" to begin ground testing soon. These will be delivered within 16 weeks of the contract’s approval. The assembly will be completed within 15 weeks while the last week will be reserved for acceptance testing.

Applications 
The fighter jet platforms that have been integrated with Uttam radar or are planned to be integrated are as follows:

 HAL Tejas Mk1/1A (Testing phase): Already integrated on Limited Series Production aircraft (LSP 2 and 3). They have completed 125 developmental flights. The radar will be directly integrated on Tejas Mk1A from the 41st production aircraft onwards.
 Hawker 800 (Testing phase)
 HAL Tejas Mk 2 (Planned)
 Sukhoi Su-30MKI (Planned): During the Super Sukhoi upgrade, the present PESA Bars radar will be replaced by the Virupaaksha radar. In the first phase, 84 units would be upgraded by Hindustan Aeronautics Limited (HAL) in India.
 Mikoyan MiG-29K (Planned)
 HAL TEDBF (Planned)
 HAL AMCA (Virupaaksha variant planned)

Gallery

See also
 HAL Tejas
 HAL Tejas Mark 2
 HAL TEDBF
 HAL AMCA
 DRDO AEW&CS
 Phased array
 Active electronically scanned array

References

Aircraft radars
Military radars of India
Defence Research and Development Organisation