Shaping the Invisible
Every wireless device depends on antennas to convert guided electrical signals into free-space electromagnetic waves — and vice versa. A single dipole radiates nearly omnidirectionally, but by arranging multiple elements into an array and controlling their relative phases, engineers sculpt the radiation pattern into focused beams that reach farther, reject interference, and serve multiple users simultaneously.
The Array Factor
The radiation pattern of a phased array is the product of the single-element pattern and the array factor. For a uniform linear array of N elements spaced d apart, the array factor is a sum of complex exponentials whose constructive interference produces a main lobe. The beamwidth narrows as N or d/λ increases, concentrating energy into a tighter angular cone and boosting directivity proportionally.
Steering and Grating Lobes
Applying a linear phase gradient across the elements steers the main beam to a desired angle without any mechanical motion. However, if element spacing exceeds one wavelength, the periodic structure creates grating lobes — parasitic beams as strong as the main lobe that waste power and cause interference. Half-wavelength spacing is the standard design choice to prevent grating lobes across the full ±90° scan range.
From Radar to 5G
Phased arrays originated in military radar during World War II and now underpin civilian technologies: 5G massive-MIMO base stations use 64–256 elements to serve dozens of users with individual beams, satellite internet constellations use flat-panel arrays for seamless tracking, and automotive radar uses small arrays for adaptive cruise control. This simulation lets you explore how element count, spacing, and steering angle interact to shape the radiated field.