Changing the direction of the main lobe of a radiation pattern
Beam steering is a technique for changing the direction of the main lobe of a radiation pattern.
In radio and radar systems, beam steering may be accomplished by switching the antenna elements or by changing the relative phases of the RF signals driving the elements. As a result, this directs the transmit signal towards an intended receiver. In recent days, beam steering is playing a significant role in 5G communication because of quasi-optic nature of 5G frequencies.
In acoustics, beam steering is used to direct the audio from loudspeakers to a specific location in the listening area. This is done by changing the magnitude and phase of two or more loudspeakers installed in a column where the combined sound is added and cancelled at the required position. Commercially, this type of loudspeaker arrangement is known as a line array. This technique has been around for many years but since the emergence of modern digital signal processing (DSP) technology there are now many commercially available products on the market. Beam steering and directivity Control using DSP was pioneered in the early 1990s by Duran Audio who launched a technology called DDC (Digital Directivity Control).
In optical systems, beam steering may be accomplished by changing the refractive index of the medium through which the beam is transmitted or by the use of mirrors, prisms, lenses, or rotating diffraction gratings. Examples of optical beam steering approaches include mechanical mirror-based gimbals or beam-director units, galvanometer mechanisms that rotate mirrors, Risley prisms, phased-array optics, and microelectromechanical systems using micro-mirrors.
Source: from Federal Standard 1037C
Beam Steering Applications and Emerging Techniques.
The scope of beam-steering technologies has broadened significantly with innovations that serve both traditional applications and emerging demands in fields such as satellite communication, radar, and 5G networks. Traditional methods like parabolic reflectors and phased arrays are now complemented by Reflectarray (RA) and Transmitarray (TA) antennas. These designs serve as high-gain, planar alternatives with advantages in cost, efficiency, and scalability, meeting modern requirements for compact and lightweight systems. One of the latest approaches in beam steering involves Near-Field Meta-Steering (NFMS), which uses phase-gradient metasurfaces placed in close proximity to a feed antenna. This method achieves 3D beam steering by employing compact structures that allow wide-angle control over both elevation and azimuth, proving highly effective for systems where space and profile height are restricted. 
Beam steering has also found essential applications in high-speed, interference-free communication for defense and civilian markets. Satellite-based communication systems, for example, require dual-band beam-steering capabilities to handle uplink and downlink data streams simultaneously. The development of beam-steering antennas for Satellite Communication on the Move (SOTM) systems highlights the need for antennas that are not only efficient but also lightweight, low-profile, and cost-effective. Challenges remain, including addressing cost constraints and achieving higher scanning speeds and wider bandwidths.
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