antennearray

An antenna array is a system composed of multiple antenna elements arranged in a specific geometry to control the radiation pattern. The total radiated field is the coherent sum of the fields from each element. By adjusting the relative amplitudes and phases of the excitations, an antenna array can steer its main lobe, shape its pattern, and suppress sidelobes, enabling directed transmission or reception without mechanically moving the structure.

Common configurations include linear arrays (one-dimensional), planar arrays (two-dimensional), and circular arrays. The elements may be dipoles, monopoles, patches, or other radiators, and spacings are typically around half a wavelength to balance issues such as grating lobes and physical size. Key concepts include the array factor, which describes the influence of geometry and excitation on the pattern, and the element pattern, which describes the intrinsic radiation of a single element. The resulting directivity and gain depend on both.

Phased arrays achieve beam steering primarily through phase shifting, while active or smart arrays incorporate power amplifiers and control circuitry at each element to enable adaptive beamforming. Practical design must consider mutual coupling between elements, impedance matching, bandwidth, and sidelobe or grating lobe levels.

Applications span radar, wireless communications, satellite links, and radio astronomy. Antenna arrays underpin modern beamforming techniques, enabling rapid, electronically steerable beams and high-gain performance in compact or large-scale systems.