Horn Antenna
A horn antenna flares a waveguide out to a larger aperture to raise gain and form a clean beam — the workhorse feed and standard-gain reference of microwave measurement. This tool estimates the gain, effective aperture and approximate beamwidths of a pyramidal or conical horn from its aperture size and frequency, using the ≈0.51 aperture efficiency of an optimum-flare horn.
Equations & Parameters ▸
\(G=\varepsilon_{ap}\,\dfrac{4\pi A}{\lambda^2},\quad \varepsilon_{ap}\approx0.51\)
\(\text{Pyramidal: }A=a\,b \qquad \text{Conical: }A=\dfrac{\pi D^2}{4}\)
\(\theta_E\approx\dfrac{56\lambda}{b}\ (^\circ),\quad \theta_H\approx\dfrac{67\lambda}{a}\ (^\circ)\)
\(\text{Pyramidal: }A=a\,b \qquad \text{Conical: }A=\dfrac{\pi D^2}{4}\)
\(\theta_E\approx\dfrac{56\lambda}{b}\ (^\circ),\quad \theta_H\approx\dfrac{67\lambda}{a}\ (^\circ)\)
| Type | Pyramidal (rectangular aperture a×b) or conical (circular aperture diameter D). |
| a | Aperture width / H-plane dimension (m), or the conical diameter D. |
| b | Aperture height / E-plane dimension (m). Ignored for a conical horn. |
| εap | Aperture efficiency; ≈0.51 for an optimum-flare horn (default). Higher for corrugated/lens horns. |
Reference: C. A. Balanis, Antenna Theory, 4th ed., Wiley, 2016 (Ch. 13, horn antennas).
Inputs
rectangular aperture
m
H-plane widthm
E-plane heightGHz
BandDefault 0.51
Results
Gain
Gain—
Effective aperture Ae—
Wavelength λ—
Beamwidth (approx.)
E-plane HPBW—
H-plane HPBW—
Diagram