What is array amplitude tapering?
Amplitude tapering (weighting) reduces the excitation of elements toward the edges of an array to lower sidelobes. The cost is a wider main beam and lower aperture (taper) efficiency. The classical designs are Dolph–Chebyshev (narrowest beam for a given equal-ripple sidelobe level) and Taylor (n̄-parameter near-in sidelobes at a chosen level, then decaying).[1][2][3]
How do tapers compare?
| Taper | First sidelobe | Beamwidth | Notes |
|---|---|---|---|
| Uniform | −13.3 dB | Narrowest | Max directivity |
| Cosine (on aperture) | −23 dB | ≈ 1.35× uniform | Taper efficiency ≈ 0.81 |
| Dolph–Chebyshev | Chosen, equal ripple | Narrowest for that SLL | Equal far-out sidelobes |
| Taylor n̄ | Chosen near-in | Near Chebyshev | Practical, decaying far-out lobes |
| Binomial (λ/2) | None | Very broad | Large dynamic range of weights |
Aperture values from Balanis and Stutzman.[3][4]
What limits achievable sidelobes?
Amplitude and phase errors from components, quantization and mutual coupling set an average sidelobe floor regardless of the design taper; very low-sidelobe arrays (−40 dB and below) require tight error budgets and calibration.[5][6]
Is tapering done in transmit and receive?
Receive tapering is easy in digital beamforming. Transmit tapering with saturated amplifiers wastes power, so radar transmitters often use uniform illumination and taper only on receive.[7]
Frequently asked questions
What is taper efficiency?
Directivity of the tapered aperture divided by that of the uniform one.
Which taper is most used in radar?
Taylor weighting is common.
Does tapering change beam pointing?
No, if symmetric.
See also
References
Online sources accessed October 21, 2026; printed works cited by edition. See all sources.
- “A Current Distribution for Broadside Arrays Which Optimizes the Relationship Between Beam Width and Side-Lobe Level”. C. L. Dolph, Proceedings of the IRE, vol. 34, no. 6, pp. 335-348. June 1946.
- “Design of Line-Source Antennas for Narrow Beamwidth and Low Side Lobes”. T. T. Taylor, IRE Transactions on Antennas and Propagation, vol. 3, no. 1, pp. 16-28. January 1955.
- “Antenna Theory: Analysis and Design, 4th ed.”. C. A. Balanis, Wiley. 2016.
- “Antenna Theory and Design, 3rd ed.”. W. L. Stutzman and G. A. Thiele, Wiley. 2012.
- “Phased Array Antenna Handbook, 3rd ed.”. R. J. Mailloux, Artech House. 2017.
- “Phased Array Antennas, 2nd ed.”. R. C. Hansen, Wiley. 2009.
- “Introduction to Radar Systems, 3rd ed.”. M. I. Skolnik, McGraw-Hill. 2001.