What is a phased array antenna?
A phased array antenna — also called an electronically steered antenna (ESA) or active electronically scanned array (AESA) — replaces a single mechanically steered dish with a flat panel containing hundreds or thousands of small antenna elements. By applying precise phase shifts to each element's signal, the system creates constructive interference in the desired beam direction and destructive interference elsewhere, effectively pointing the antenna beam without any moving parts.
How beam steering works
The central beam steering controller adjusts phase shifters connected to each element. When elements on one side of the array transmit with a slight phase advance over the opposite side, the combined wavefront tilts, redirecting the beam. Modern digital beamforming systems process signals in the digital domain, enabling simultaneous formation of multiple independent beams pointing in different directions — critical for satellite systems serving many users at once.
Advantages over parabolic dishes
Electronic steering is orders of magnitude faster than mechanical steering — beam repositioning in microseconds vs. seconds for a dish motor. Phased arrays can track multiple satellites simultaneously, switch between LEO satellites seamlessly during handoff, and survive vibration environments that would damage gimballed dish motors. They are also thinner and lighter, enabling installation on vehicles, aircraft, and maritime vessels where a dish would be impractical.
Role in LEO broadband
The Starlink flat-panel terminal, Viasat's ArcLight, and Hughes Jupiter terminals are phased array systems. Their ability to track a moving LEO satellite across the entire sky — without a motor — is what makes consumer-grade LEO broadband terminals practical. The mass production of phased array chips (driven by Starlink's scale) has dramatically reduced costs since 2019.