What is a horn antenna?
A horn antenna is a flared section of waveguide that transforms the guided wave to a larger radiating aperture. Pyramidal, sectoral, conical, corrugated and ridged horns provide gains from about 10 to 25 dBi with well-predicted patterns and wide bandwidth, which is why standard gain horns are the reference antennas of gain measurement.[1][2]
What types of horn are there?
- E-plane and H-plane sectoral: flared in one plane only.
- Pyramidal: flared in both planes; the classic standard gain horn.
- Conical: fed by circular waveguide; supports dual or circular polarization.
- Corrugated (scalar): grooves in the walls create a hybrid HE11 mode with symmetric beams, low sidelobes and very low cross-polarization; the preferred feed for reflectors.[3]
- Double-ridged: ridges lower the cutoff for multi-octave bandwidth, used in EMC and wideband measurement.[4]
How is horn gain calculated?
G = eap·4πab/λ² for a pyramidal horn with aperture a × b. Phase error across the flared aperture limits gain for a given length; an optimum horn chooses flare dimensions for maximum gain at a given axial length and achieves an aperture efficiency of about 0.51.[1]
Where are horns used?
As reflector feeds, standard gain references, EMC and radar measurement antennas, mmWave and satellite payload antennas, and as elements of some arrays. Their main limitation is size and weight at lower frequencies.[3][5]
Frequently asked questions
Why do horns have such accurate gain?
Their gain follows closely from aperture theory and can be computed to a few tenths of a dB.
What is the phase center of a horn?
The apparent point from which spherical waves emanate; it lies inside the horn and varies with frequency.
Are horns broadband?
Pyramidal horns cover their waveguide band; ridged horns cover 10:1 or more.
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.
- “IEEE Recommended Practice for Antenna Measurements (IEEE Std 149-2021)”. IEEE Antennas and Propagation Society. 2022.
- “Microwave Horns and Feeds”. A. D. Olver, P. J. B. Clarricoats, A. A. Kishk and L. Shafai, IEE/IEEE Press. 1994.
- “Antenna Engineering Handbook, 4th ed.”. J. L. Volakis (ed.), McGraw-Hill. 2007.
- “Antenna Theory and Design, 3rd ed.”. W. L. Stutzman and G. A. Thiele, Wiley. 2012.