What is an antenna array?
An antenna array is a set of radiating elements whose amplitudes and phases are controlled so that their fields combine constructively in desired directions and destructively in others. For identical elements, the total pattern is the element pattern multiplied by the array factor (pattern multiplication), and an N-element array can provide up to N times (10·log10N dB) the element directivity.[1][2]
What is pattern multiplication?
If all elements are identical and identically oriented, the far field is Etotal = Eelement(θ,φ) × AF(θ,φ), where AF depends only on positions and excitations. In real arrays mutual coupling makes edge and center elements differ, so the embedded (active) element pattern replaces the isolated one.[1][3]
What are broadside and endfire arrays?
A uniform linear array with equal phases radiates broadside (perpendicular to the axis). With a progressive phase β = −kd, it radiates endfire along the axis; the Hansen–Woodyard condition adds extra phase to increase endfire directivity.[1] Yagis are parasitic endfire arrays; collinears are broadside.
What array geometries are common?
- Linear: one-dimensional scanning or fan beams.
- Planar rectangular or triangular grids: pencil beams scanned in two planes; triangular grids allow about 13% fewer elements for the same grating-lobe-free scan.[2]
- Circular and conformal arrays: 360° coverage, curved platforms.
- Sparse and thinned arrays: fewer elements with controlled sidelobes.
Frequently asked questions
Does doubling elements double gain?
Ideally +3 dB if the aperture doubles, ignoring feed losses and coupling.
Can elements be different?
Yes, but pattern multiplication then no longer applies directly.
What spacing is typical?
About λ/2 for scanning arrays, to avoid grating lobes.
See also
References
Online sources accessed October 21, 2026; printed works cited by edition. See all sources.
- “Antenna Theory: Analysis and Design, 4th ed.”. C. A. Balanis, Wiley. 2016.
- “Phased Array Antenna Handbook, 3rd ed.”. R. J. Mailloux, Artech House. 2017.
- “The Element-Gain Paradox for a Phased-Array Antenna”. P. W. Hannan, IEEE Transactions on Antennas and Propagation, vol. 12, no. 4, pp. 423-433. July 1964.