AESA radar
Active electronically scanned array radar, which steers its beam electronically using many small transmit and receive modules instead of a rotating antenna.
An active electronically scanned array (AESA) radar is a radar whose antenna is made of many small transmit and receive elements, each with its own electronics. The beam is pointed by controlling the timing, or phase, of the signal at each element, so it can be moved almost instantly without physically moving the antenna. This differs from a mechanically scanned radar, which sweeps a single dish or flat plate on a gimbal, and from a passive electronically scanned array, which steers a beam electronically but feeds all elements from one central transmitter.
How it works
Each element of the array is paired with a transmit/receive (TR) module, usually containing a phase shifter, switching circuits and amplifiers. Because the modules generate and amplify the signal at the element itself, the array can form several beams at once, divide its elements into groups with different jobs, change its waveforms rapidly, and keep working with a degraded set of modules. These properties let one radar interleave search, tracking and other functions that would otherwise need separate sensors. Modern designs add digital beamforming, where signals are combined in software, which moves more of the radar’s behaviour into processing and makes upgrades largely a software matter.
Technology and history
Early AESAs used gallium arsenide semiconductors. Gallium nitride, which tolerates higher voltage and temperature, is now being introduced in newer and upgraded radars, according to Navy technical material. The first operational fighter radars of this type entered service around 2000, and the technology has since spread to fighter aircraft, ships, ground-based air defence and surveillance systems. The F-35’s radar is an example: the programme office says it has well over a thousand modules and a solid-state design with no moving parts, which it expects to improve reliability and reduce life-cycle cost compared with mechanically steered radars. The US Navy’s AN/SPY-6 family for ships is built from modular assemblies, which lets the same design be scaled to different hull sizes.
Who uses it
Air forces, navies and armies in most advanced militaries operate AESA radars, and several European, Asian and North American suppliers produce them. Applications include air-to-air and air-to-surface sensing on fighters, air and missile defence on warships, ground-based surveillance, and airborne early warning.
Why it matters for defence technology
AESA radars are costly, export-controlled systems whose performance is determined as much by software and signal processing as by hardware. They also function as data sources for sensor fusion, and as emitters and receivers they overlap with electronic warfare, since the same array can in principle be used for radar and certain electronic support roles. Their modularity matters for sustainment: replacing modules and updating software can extend a radar’s service life, which the F-35 programme office says could reach about twice the expected life of the airframe.
What to watch
Areas to follow include the spread of gallium nitride, smaller arrays suited to uncrewed aircraft such as collaborative combat aircraft, software-defined upgrades, cost reduction, and export approvals. Public performance figures are rarely released, so claims about range or resolution should be treated with caution unless an official source gives them.
Sources
Related: Collaborative combat aircraft · Electronic warfare · Intelligence, surveillance and reconnaissance (ISR) · Sensor fusion