Antenna Gain Calculator

Calculate parabolic antenna gain in dBi online, supporting multi-band and multi-type antennas, with detailed calculation formulas and performance analysis.

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Tool Usage

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Set parameters first, then view results

Estimate dBi, beamwidth, EIRP, and link margin by antenna size, frequency, efficiency, or known gain

Select a calculation model first, then enter frequency, antenna size, and loss parameters. Switch to results to view formulas, sweep charts, and export reports.

Current calculation snapshot Not calculated

-- Nominal gain

-- Half-power beam

-- Estimated EIRP

-- Link margin

Select a calculation model and enter basic parameters

The aperture model is for aperture antennas such as dishes, horns, and planar arrays. If no size is available, use known gain or beamwidth to work backward.

Frequency and antenna type Frequency affects wavelength, gain, and far-field distance

Antenna Type

Operating Frequency

Efficiency/Aperture Efficiency

Beam Factor K

Aperture Size Use diameter for circular apertures; width and height for rectangular apertures

Aperture Shape

Antenna Diameter D

Aperture Width

Aperture Height

Surface RMS Error

Beamwidth Input Uses engineering approximation D≈41253/(θE×θH)

E-plane HPBW

H-plane HPBW

Beam Estimate Correction

Known Gain Input For unit conversion, effective aperture, and link budget

Gain Value

Gain Unit

Measured HPBW

Array parameters Array gain ≈ element gain + 10log10(N×array efficiency) - combining loss

Element gain

Element count N

Array efficiency

Combining/feed loss

Set losses, polarization, and link budget parameters

These parameters do not change the antenna's nominal physical gain, but affect usable gain, EIRP, received power, and link margin.

Antenna-end loss Enter feeder, mismatch, and polarization values based on measurements or system budget

Feeder/connector loss

Radome/blockage loss

VSWR

Polarization match

Custom polarization loss

Propagation margin

Custom path margin

Target received power

Transmit, distance, and receiver Used to estimate EIRP, free-space loss, received power, and noise margin

Transmit power

Link distance

Receive antenna gain

Extra receiver loss

System noise temperature

Channel bandwidth

Receiver noise figure

Pointing/tracking loss

View calculation results, formulas, and parameter sweeps

Results update with parameters in real time; sweep charts help compare effects of frequency, size, efficiency, or distance changes.

Nominal antenna gain

Linear factor --

Actual usable gain

Total loss --

Half-power beamwidth

First-null beam --

Link margin

Received power --

Detailed metrics Band pending calculation

Formulas and assessment Engineering approximation, suitable for planning estimates

Please set parameters and click Calculate first.

Parameter sweep Shows trends in key metrics as parameters change

Default: sweep nominal gain over the current frequency range.

Sweep parameter

Samples

Start value

End value

Instructions

Software Usage Instructions

Select a calculation model: In the parameter settings, choose aperture/reflector model, beamwidth estimation, known gain conversion, or array gain estimation.
Enter basic parameters: Input the operating frequency, frequency unit, antenna type, and efficiency; for the aperture model, you can set a circular diameter or rectangular width and height.
Configure losses and link: Enter parameters such as feed line loss, VSWR, polarization loss, transmit power, link distance, receive gain, and target received power.
View result analysis: After clicking calculate, view dBi gain, actual usable gain, beamwidth, effective aperture, far-field distance, EIRP, received power, and link margin.
Use parameter sweep: Select frequency, size, efficiency, or distance as the sweep parameter to observe how gain or received power changes with the parameter.
Save and export: You can save the current settings, copy the calculation results, or download a CSV report for recording and comparison.

FAQ

A: dBi is the gain relative to an ideal isotropic antenna, while dBd is the gain relative to a half-wave dipole. The common conversion is dBi = dBd + 2.15.

A: Typical values are 55%-75% for parabolic antennas, 60%-85% for horn antennas, and 40%-75% for microstrip antennas. If measured data is available, the measured efficiency should be used first.

A: With a fixed physical size, a higher frequency means a shorter wavelength, making the antenna electrically larger, so aperture gain increases. However, high-frequency links are also more susceptible to path loss, rain attenuation, and installation errors.

A: Half-power beamwidth reflects the coverage angle of the main lobe. The smaller the value, the stronger the directivity, and the higher the pointing requirements for point-to-point links or satellite antennas.

A: EIRP is typically equal to the transmit power plus the actual usable antenna gain, minus losses such as feed line, mismatch, polarization, and pointing losses. It is used to represent the system’s equivalent radiated capability.

A: The calculation results are suitable for solution estimation and parameter comparison. Engineering finalization should also take into account measured radiation patterns, VSWR, feed line losses, installation environment, regulatory limits, and link test data.