Antenna array
Multiple antennas working together to form a single, directional antenna.
An antenna array, also called an array antenna, is a group of interconnected antennas that function as one unit for sending or receiving radio waves. Each individual antenna in the group is known as an element, and these elements are typically linked to a single transmitter or receiver via feedlines that deliver power with a carefully controlled phase relationship. When transmitting, the radio waves from each element combine and overlap. They add together through constructive interference to boost power in certain directions, and cancel each other out through destructive interference to reduce power in others. On the receiving side, the separate radio frequency currents from the elements combine in the receiver with the correct phase to strengthen signals from desired directions and suppress signals from unwanted ones. More advanced array antennas may use multiple transmitter or receiver modules, each connected to a single element or a group of elements.
An antenna array can provide higher gain, or directivity, than a single element, producing a narrower beam of radio waves. Generally, using more elements increases the gain and narrows the beam further. Some arrays, like military phased array radars, contain thousands of individual antennas. Arrays serve many purposes: achieving higher gain, providing path diversity (known as MIMO) for more reliable communication, canceling interference from specific directions, electronically steering the radio beam without moving parts, and performing radio direction finding (RDF).
The term "antenna array" most often refers to a driven array, made up of multiple identical driven elements all connected to the receiver or transmitter. A parasitic array, by contrast, has only one driven element connected to the feedline, with other elements that are not connected—these are called parasitic elements. This is another name for a Yagi–Uda antenna. A phased array usually means an electronically scanned array: a driven array where each element is connected to the transmitter or receiver through a computer-controlled phase shifter. This allows the radio beam to be steered electronically, instantly pointing in any direction over a wide angle without moving the antennas. However, the term "phased array" is sometimes used simply to mean an ordinary array antenna.
- Types
- broadside array, endfire array, driven array, collinear array, superturnstile (batwing) array, circularly-disposed antenna array (CDAA), planar array, reflective array, curtain array, microstrip array
- Principle
- directivity proportional to wavelength divided by antenna width (Rayleigh criterion)
- Beam characteristics
- main lobe plus weaker sidelobes
Lore & Background
The principle behind an antenna array relies on interference: for a transmitting antenna, the electromagnetic wave at any point is the vector sum of waves from each element. If currents are fed with proper phase, spherical waves combine to create plane waves traveling in a specific direction. When receiving, oscillating currents from desired directions are in phase and reinforce each other, while currents from other directions are out of phase and cancel. The radiation pattern consists of a strong main lobe and weaker sidelobes. Larger arrays with more elements produce narrower main lobes and higher gain.
Arrays are categorized by how the component antennas' axis relates to the radiation direction. A broadside array radiates perpendicular to the plane of the antennas, requiring in-phase feeding. An endfire array radiates along the line of the antennas, requiring a phase difference equal to the element separation. Some arrays, such as phased arrays, do not belong to either category. Driven arrays have all elements connected to the transmitter or receiver. Parasitic arrays, another name for Yagi-Uda antennas, have a single driven element and other parasitic elements.
Notable types include the collinear array (multiple vertical dipoles for high-gain omnidirectional use), the superturnstile or batwing array (used for television broadcasting), the circularly-disposed antenna array (CDAA) for direction-finding, and the curtain array (a planar array of wire dipoles for shortwave broadcasting). The largest array antennas are radio interferometers used in radio astronomy, where multiple large parabolic antennas are linked together; using aperture synthesis, such arrays can achieve resolution equal to an antenna with a diameter equal to the distance between the antennas. Very Long Baseline Interferometry (VLBI) links dishes on separate continents, creating arrays thousands of miles in size.
Reader's Guide
The antenna array is a foundational concept in radio engineering, enabling directional control and high gain that single elements cannot achieve. Its significance lies in its versatility: arrays can be used to achieve higher gain, provide path diversity (MIMO) for increased communication reliability, cancel interference from specific directions, steer radio beams electronically, and perform radio direction finding (RDF). The phased array, an electronically scanned array where each element is connected through a computer-controlled phase shifter, allows the beam to be steered instantly without moving the antennas. This technology is employed in military phased array radars composed of thousands of individual antennas. The legacy of antenna arrays extends to radio astronomy, where interferometric arrays using aperture synthesis have dramatically increased resolution, with VLBI linking telescopes across continents. The ability to combine multiple elements—whether simple dipoles, Yagi antennas, or patch antennas on printed circuit boards—has made arrays ubiquitous in applications from television broadcasting and two-way radio to radar and space communications. The trade-off between array size, number of elements, beam width, and sidelobe levels remains a central design consideration.
Did You Know?
- The term 'antenna array' most commonly means a driven array of multiple identical driven elements all connected to the receiver or transmitter.
- A parasitic array is usually another name for a Yagi–Uda antenna.
- The largest array antennas are radio interferometers used in radio astronomy, with dishes linked across continents via Very Long Baseline Interferometry (VLBI).
- Circularly-disposed antenna arrays (CDAAs) are used for direction-finding and have earned the nickname 'elephant cages'.
Frequently Asked Questions
What is an antenna array?
An antenna array is a group of individual antenna elements wired together so they act as one combined transmitter or receiver. Each element ties into a shared feed source through feedlines that hold a precise phase relationship, letting the whole group behave as a single directional antenna.
How does an antenna array focus its signal in one direction?
The waves radiated by each element overlap and reinforce one another through constructive interference in the desired direction while canceling out through destructive interference elsewhere. That interference pattern is what carves the array's radiation into a tight, directional beam.
What types of antenna arrays exist?
Common geometries include broadside, endfire, collinear, planar, reflective, curtain, and microstrip arrays, along with specialized designs such as the circularly-disposed antenna array (CDAA) and the superturnstile (batwing) array. The chosen layout determines whether the main beam points broadside to the element line or along it.
What does the beam pattern of an antenna array look like?
The radiation pattern features a strong main lobe in the intended direction flanked by weaker sidelobes at other angles. The array's directivity follows the Rayleigh criterion, which ties it to the ratio of the operating wavelength to the overall array width.
Why do engineers reach for an antenna array instead of one big single antenna?
Arrays let designers tune beamwidth, directivity, and sidelobe levels by adjusting element count, spacing, and phase offsets rather than simply scaling up a single element. That modularity makes arrays practical for radar, point-to-point links, and other applications where a monolithic antenna would be unwieldy or impossible to build.
More in Antenna Types 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced