An Active Electronically Scanned Array (AESA) radar replaces the single, mechanically steered antenna of older fighter radars with hundreds or thousands of small transmit/receive modules, each capable of independently steering its beam electronically. This gives AESA radars far greater agility, reliability and resistance to jamming than the passive electronically scanned arrays and mechanically scanned dishes they replace. India's indigenous entry in this class is Uttam, developed by DRDO for the Tejas Light Combat Aircraft family.

Key facts

  • Type: Active Electronically Scanned Array (AESA) fire-control radar
  • Developer: DRDO's Electronics and Radar Development Establishment (LRDE), with Bharat Electronics Limited (BEL) as production partner
  • Band: X-band
  • Transmit/receive modules: over 980 in the finalised Uttam design, up from an initial 720
  • Detection range: beyond 100 km against fighter-sized targets, with a Tejas-sized target tracked at 140 km in trials
  • Platforms: HAL Tejas Mk1A, entering production aircraft from the 41st jet, and the planned Tejas Mk2

How AESA radar works

Unlike a conventional radar dish that must physically rotate or tilt to point its beam, an AESA antenna is built from a large number of small transmit/receive modules arranged in a flat array. Each module can shift the phase of its signal independently, allowing the combined beam to be steered electronically across a wide field of view in milliseconds, with no moving parts. This lets an AESA radar interleave search, track and targeting functions almost simultaneously, follow many more targets at once, and adapt its transmissions to reduce the chance of being detected or jammed by an adversary. Because the antenna has no moving parts and the beam is formed from many independent modules, an AESA radar also degrades gracefully: the loss of a handful of transmit/receive modules causes a small dip in performance rather than the outright failure that can affect a mechanically scanned dish.

Development of Uttam

Work on the Uttam AESA radar began at LRDE in 2008 as part of India's effort to equip Tejas with an indigenous, world-class sensor rather than relying solely on imported radars. The baseline Mk-1 design uses gallium arsenide (GaAs) semiconductor technology in its transmit/receive modules, arranged in a modular quad-plank configuration that allows the same building blocks to be scaled up or down for different aircraft. DRDO has stated the radar is roughly 95 percent indigenous in content. A technology-transfer arrangement with Hindustan Aeronautics Limited, concluded around Aero India 2021, paved the way for Uttam to be manufactured and integrated into production Tejas Mk1A jets.

Capabilities

Uttam supports around 18 operating modes spanning air-to-air, air-to-ground and air-to-sea roles, giving Tejas pilots simultaneous long-range search and multi-target tracking together with ground-mapping, terrain-following and maritime-surveillance functions in a single radar. Because its beam is steered electronically rather than mechanically, it can maintain track on multiple threats while continuing to scan for new ones, and its solid-state design is intended to keep failure rates low and ease maintenance compared with older mechanically scanned radars.

The Mk-2 upgrade

A follow-on Uttam Mk-2 variant is being developed with gallium nitride (GaN) transmit/receive modules in place of gallium arsenide, offering greater transmit power, better thermal performance and improved detection range within a similar physical envelope. This version, described with a wider-angle swashplate antenna arrangement giving a field of view beyond 100 degrees, is intended for the larger and more powerful Tejas Mk2.

Uttam's progress is widely seen as a benchmark for India's broader ambition to design and produce AESA radars domestically for future fighters, naval platforms and ground-based air-defence systems, reducing dependence on imported sensors that Tejas has also flown with during trials. The programme has also fed wider design and manufacturing expertise back into LRDE and BEL, supporting parallel indigenous AESA efforts aimed at other combat aircraft, naval fire-control systems and next-generation ground-based air-defence radars.