Electronically Scanned Array
Understanding ESAs
Electronically scanned arrays represent the state of the art in antenna technology. By eliminating mechanical scanning, they achieve beam agility that is impossible with reflector antennas. An AESA can switch between beams, form multiple simultaneous beams, and adaptively null interference sources.
AESA vs PESA
- AESA (Active): T/R module at each element. Each element has its own PA and LNA. Higher cost but better performance, graceful degradation, and reliability.
- PESA (Passive): Centralized PA/receiver with phase shifters at each element. Lower cost but single point of failure at the central PA. Less flexible.
ESA Applications
- Military radar: AESA is standard for modern fighter aircraft (F-22, F-35), naval radar (SPY-6), and ground-based systems.
- 5G: Massive MIMO base stations use hundreds of elements for beamforming.
- Satellite: LEO constellation terminals use ESAs to track fast-moving satellites.
Frequently Asked Questions
What is an ESA?
An ESA steers its beam electronically by adjusting phase at each element, without mechanical movement. Active ESAs (AESA) have amplifiers at each element. They can switch beams in microseconds and track multiple targets simultaneously.
What is the advantage of AESA over PESA?
AESA distributes amplification to each element, eliminating the feed network loss and single-point-of-failure central PA. If individual elements fail, the array degrades gracefully. AESA also enables independent frequency/waveform from each element.
How fast can an ESA steer?
ESAs can switch beam direction in microseconds (determined by phase shifter switching speed). This is thousands of times faster than mechanical scanning. A radar ESA can interleave search, track, and electronic warfare functions on a pulse-by-pulse basis.