Antenna Gain Rechner
Berechnen Sie parabolic antenna gain in dBi aus dish diameter, frequency, and efficiency.
Gain
41.0 dBi
Gain vs Dish Diameter
Formel
How Parabolic Antenna Gain is Calculated
Antenna gain measures how effectively the dish concentrates energy compared to an isotropic radiator.
Formula
G = eta x (pi x D / lambda)^2
G(dBi) = 10 x log10(G)
Where D is diameter, lambda is wavelength (c/f), and eta is aperture efficiency (typically 0.5 to 0.7).
The beamwidth approximation is theta = 70 x lambda / D degrees.
Lösungsbeispiel
A 1.2 m dish at 12 GHz with 55% efficiency.
- 01Wavelength: 0.3 / 12 = 0.025 m
- 02pi x D / lambda = 3.1416 x 1.2 / 0.025 = 150.8
- 03G linear = 0.55 x 150.8^2 = 0.55 x 22,741 = 12,508
- 04G dBi = 10 x log10(12508) = 40.97 dBi
- 05Beamwidth: 70 x 0.025 / 1.2 = 1.46 degrees
Häufig Gestellte Fragen
What is aperture efficiency?
It accounts for feed illumination, spillover, surface accuracy, and blockage. Typical values range from 50-70% for standard dishes.
Does higher frequency always mean more gain?
For a fixed dish size, yes. Higher frequency means shorter wavelength, so the dish captures more wavelengths across its aperture.
What is dBi?
Decibels relative to an isotropic (omnidirectional) antenna. A gain of 40 dBi means 10,000 times more focused than omnidirectional.
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