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Horn Antenna

Aperture Antennas

A flared waveguide that radiates a clean, directive beam at microwave frequencies.

Band: Microwave (UHF to mmWave)
Gain: ~10-25 dBi (aperture dependent)
Polarization: Linear (set by waveguide mode)

Photos

Real-world photo of a Horn Antenna in use — Real-world example. Source: Wikimedia Commons (Public domain; NASA, restored by Bammesk).

Radiation / wave patterns

Idealized radiation pattern of the Horn Antenna — Idealized azimuth radiation pattern (illustrative, generated). Radial scale in dB.

How & why it works

A horn antenna is a section of waveguide flared open at the end. The gradual flare transitions the guided wave to free space with a smooth impedance match, producing low reflections and a well-behaved, predictable radiation pattern. Larger apertures yield higher gain and narrower beams, which is why horns are popular reference and feed antennas.

Real-world uses

Feeds for parabolic dish reflectors, gain-calibration standards, radar, and satellite ground stations.