Phased Arrays: From WWII Radar to LEO Satellites
Background
The development of wireless scanning technology began in the late 19th century, with fixed narrow beams produced by high-gain antennas. During World War II, the invention of radar enabled high-gain antennas to rotate mechanically, scanning the beam to achieve full 360° coverage.
To eliminate mechanical rotation, extend equipment lifespan, and improve multi-target tracking capability, PESA (Passive Electronically Scanned Array) technology was introduced in the 1960s. Starting from the 1980s, as high-frequency semiconductor technology matured, various AESA (Active Electronically Scanned Array) implementations followed.
While each new generation of wireless scanning technology is more complex than the last, system performance — detection range, resolution, tracking capability, and reliability — has improved dramatically with each generation.