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Active Electronically Scanned Array: past, present, and future

The CROWN project is an opportunity to explore innovative AESA concepts and to define the best trade-offs and solutions for future digital wideband multifunction RF systems. In particular, the AESA digitization at radiating element level, already happening for the land systems, could be a real game changer for airborne platforms. Today we talk about the AESA technology with Isabelle Le Roy Naneix, one of the experts of the CROWN project.

Isabelle, tell us what is an AESA technology?

AESA stands for Active Electronically Scanned Array. This technology is used for combat and surveillance radars on airborne, ground, or naval platforms.

AESA technology enables the integration of radar, EW, and communication functions into a single system. The AESA system combines a subset of functions one hand enabling the radiation of the Electromagnetic (EM) waves, whereas on the other implementing the combined Radar, EW and Comms functionality. Thanks to the RF Front-End part (RFFE), composed of an assembly of several hundred of Transmit/Receive modules (T/R Module), it is made possible to generate an actively steered pencil beam featuring high gain, low level of side lobesn and digital scanning.

By individually controlling the TR Modules, the active antenna uses AESA technology to steer the radar beam at the speed determined by the electronic hardware. It is the electronic scanning in space domain. The system thus overcomes the mechanical orientation constraints of a single antenna. It can thus track multiple targets instantly in multiple directions.

The active antenna therefore replaces the conventional antenna of previous generation radars and its mechanical orientation system, the radar transmitter and the first signal reception stage.

What are the major advantages of the AESA system?

The major advantages of AESA technology are operational. For instance, airborne AESA radars track all targets in their environment and do not lose them regardless of target or fighter movement.

On the other hand, their construction allows a significant increase in the detection distance of enemy aircraft and an equally significant increase in reliability compared to previous generation radars.

In air-to-air mode, better range can detect farther or detect smaller targets. For reliability, the antenna being made up of many active modules, the failure of a few of them has no perceptible consequence on the general performance of the system. Thereby, the active “front-end” only requires a maintenance operation every 10 years or more, thus increasing the availability of the aircraft and reducing the cost of spare parts.

Finally, the use of active antennas has opened new horizons in terms of the evolution of radar functions, particularly in the field of resistance to jamming, the detection of vehicles or aircraft at low speed or the improvement of “photos” radar (SAR images).

For what purpose was the technology started to develop?

AESA radar technology serves several purposes. It allows combat aircraft to have considerably increased detection capability, which in turn allows them to fully utilize the capabilities of long-range air-to-air missiles. This technology also allows the radar to track in air-to-air mode several dozen tracks while simultaneously engaging multiple targets. In addition, the use of several hundred transmitter/receiver modules makes it possible to specialize them. Thus, an AESA radar can simultaneously be used in air-air and air-ground mode or even in air-sea mode.

Furthermore, an AESA radar is more powerful and more discreet. It works on a wide spectrum of frequencies which allows it to emit signals that stand out less from the ambient noise. It can also generate very high-resolution synthetic aperture images useful for ISR missions. The fact of operating in air-to-ground mode thus provides the aircraft with a terrain-following capability allowing the real-time development of 3D maps necessary for flight at very low altitude.

AESA also makes it more difficult to jam the radar when it can itself be used for electronic attack. Finally, a significant point for the Forces, this technology is of interest for the frequency of maintenance. Indeed, the fact that some modules are faulty does not affect the performance of the radar.

What is the pace of development of AESA technology now?

The development of the first AESA technologies dates back some thirty years. While reducing their time, these developments continue to innovate in the face of the changing threat spectrum to guarantee air superiority for Armed Forces equipped with AESA radar.

What are the biggest challenges that manufacturer's face during the development of AESA radar technology?

Developments in AESA technologies are multiplying and in innovative ways. The challenges consist of selecting proposals for advanced studies that allow the results to confirm the relevance of such and such an idea to push them further. Ultimately, this constitutes a base allowing the rise in maturity of technological breakthroughs while reducing development times.

How widely the AESA technology is applied? In which sectors?

AESA technologies apply to radars of all types: long and medium-range surveillance or observation radars, or surveillance and fire control radars. Applications also relate to communications.

What is the future of AESA?

In the future, AESA will make it possible to share antennas to minimize their number on the platforms. These antennas will be able to fulfil the functions of radar, electronic warfare, and communication.

They can also be distributed in different locations on the platforms and will increase performance in terms of angular coverage, time and space sharing, very high-resolution processing, interweaving of different frequency bands. These benefits will be made possible by highly modular architectures, multi-channel capacities backed by a multiplication of sub-networks on the same antenna, going as far as a sub-network reduced to the radiating element. This requires continuing work on the miniaturization of transmission/reception chains by exploiting GaN and SiGe technologies and by developing European production lines for digital technologies (DAC/ADC, ASIC, etc.).


Mrs Isabelle Le Roy Naneix received the engineer’s degree in Electronics from ENSEEIHT in 1990 and the PhD in Electronic from the University of Toulouse (INPT) in 1993. She joined THALES Defense Mission Systems in 1996 and has been involved, over 20 years’ experience, in various development of hardware for airborne, space and naval sensors. Her main interests include array antennas, UWB antennas, electromagnetic analysis, stealth technology, multifunction RF sensors and AESA technology.


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