beamforming

Beamforming is a signal processing technique used to direct the reception or transmission of signals by combining signals from an array of antennas or sensors so that signals from a desired direction add constructively while signals from other directions are attenuated. By adjusting the relative phases and amplitudes of the signals at the sensors, the array creates a directional response that can be steered toward specific angles without physically moving the hardware.

Beams can be formed in the analog domain, with fixed hardware phase shifters and combiners, or digitally, by sampling sensor outputs and applying time delays and weighting in software. Successful beamforming relies on knowledge of the array geometry and the signal propagation medium, and it often requires calibration to compensate for sensor differences and mutual coupling.

Common approaches include conventional delay-and-sum beamforming, which aligns signals from a chosen direction and sums them, and adaptive methods such as MVDR or minimum-variance distortionless response, which attempt to suppress interference and noise from other directions. Hybrid and synthetic aperture techniques can extend performance for large arrays.

Applications span wireless communications (antenna arrays in 4G/5G and millimeter-wave systems), radar and sonar, acoustic sensing (microphone arrays, hearing devices), and medical imaging. Beamforming improves signal-to-noise ratio, increases spatial selectivity, and enables interference rejection, but it requires careful design and docking with real-world conditions, including calibration, computational resources, and array nonidealities.

A brief history note: the concept emerged from radar and sonar development in the mid-20th century and matured with digital signal processing in the late 20th century.