PhasedArray

A phased array is an arrangement of multiple radiating elements in which the relative phases and amplitudes of the signals feeding the elements are controlled to form and steer a directed beam electronically. By adjusting the phase of each element, the resulting field can be made to add constructively in a chosen direction and destructively elsewhere, enabling beam steering without moving the antenna.

In a uniform linear array with element spacing d and wavelength λ, the phase difference between adjacent elements required to steer the main lobe to angle θ is Δφ = (2π/λ) d sin θ. Planar and conformal arrays use two-dimensional phase gradients or delay profiles to steer beams in azimuth and elevation. Arrays may be passive or active, with phase shifters distributed at each element or centralized and distributed through feed networks. Digital beamforming uses sampled signals and software to form multiple beams, while analog beamforming relies on fixed or slowly tunable RF phase shifts.

Common configurations include linear, planar, circular, and conformal arrays. Key design considerations include element spacing (often λ/2 to avoid grating lobes), mutual coupling, bandwidth, and amplitude tapering to control sidelobes.

Applications span radar, satellite and terrestrial communications, wireless networks (notably 5G MIMO), sonar and acoustic imaging, and radio telescopes. Phased arrays enable fast, flexible beam steering and dynamic beam shaping, making them foundational in modern RF, microwave, and acoustic systems. History encompasses early 20th-century concepts and mid- to late-20th-century practical radar implementations, expanding into widespread use in contemporary technology.