Parabolic Antenna Gain Calculator. A parabolic dish antenna focuses radio waves into a tight beam — the larger the dish and higher the frequency, the more gain it produces. Enter your antenna diameter, operating frequency, and antenna efficiency into the Parabolic Antenna Gain Calculator to get the antenna gain in dB. Secondary outputs include 3dB beamwidth, wavelength, and half power beamwidth. Also try the Pi Attenuator Calculator.
Parabolic antenna gain is the measure of how much the antenna boosts signal strength compared to an isotropic antenna. It's calculated using the antenna diameter, operating frequency, and efficiency factor, typically expressed in dBi (decibels relative to isotropic). See also our calculate R1 (High Impedance), R1 (Low Impedance) & Voltage Ratio — Reflection Attenuator.
Typical parabolic antenna efficiency ranges from 50-80%. For professional VSAT dishes, use 65-75%. For consumer satellite dishes, use 55-65%. Higher quality dishes with better surface accuracy achieve higher efficiency.
Higher frequencies result in higher antenna gain for the same dish size. This is because the antenna becomes electrically larger relative to the wavelength. However, higher frequencies also suffer more from atmospheric attenuation and require more precise pointing.
The 3dB beamwidth is the angular width of the antenna beam where the signal strength drops to half power (-3dB). It determines the antenna's directivity and pointing accuracy requirements. Smaller dishes have wider beamwidths.
Yes, this calculator works for any parabolic reflector antenna including satellite TV dishes, VSAT antennas, and radio astronomy dishes. Just enter the dish diameter and operating frequency for your specific application.
Common VSAT dish sizes are 0.75m, 1.2m, 1.8m, and 2.4m. Larger dishes provide higher gain and better performance but cost more and require sturdier mounting. 1.2m is most common for Ku-band VSAT systems.
Surface accuracy affects efficiency. For good performance, surface deviations should be less than λ/16 (wavelength divided by 16). At 14 GHz, this means surface accuracy better than ±1.3mm for optimal efficiency.
dBi measures gain relative to an ideal isotropic antenna, while dBd measures gain relative to a dipole antenna. dBi is 2.15 dB higher than dBd for the same antenna. This calculator uses dBi which is the standard for satellite applications. You might also find our find Series Resistance (R1) with Balanced Attenuator Calculator useful.