Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Gain (dBi)

Measured realized or absolute gain.

Directivity (dBi)

Directivity of the same aperture.

Infer antenna radiation efficiency in percent from measured gain and directivity via efficiencyPercent = 10^((gainDbi - directivityDbi) / 10) * 100. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Radiation Efficiency (%)

Radiation efficiency expressed as a percentage.

• Antenna formulas assume stated frequency, impedance match, polarization, efficiency, aperture, and propagation geometry. Nearby objects, ground, feed loss, multipath, regulatory averaging, near-field conditions, and pattern variation can make free-space or ideal-aperture results inaccurate.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

• Directivity From Gain

  Recover antenna directivity as directivityDbi = gainDbi - 10 * log10(efficiencyFraction), with efficiency defaulting to 0.6.

• Antenna Radiation Efficiency

  Calculate radiation efficiency as radiated power divided by accepted power ×100. Mismatch loss before power is accepted at the antenna port is not included.

• Antenna Efficiency %

  Compute antenna efficiency as radiation resistance over total resistance, expressed as a percentage.