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.

Wavelength (m)

Operating wavelength.

Dish Diameter (m)

Reflector diameter.

Approximate parabolic dish half-power beamwidth in degrees as bwDegrees = 70 * wavelengthMeters / dishDiameterMeters. 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]

Beamwidth (°)

Half-power beamwidth between the -3 dB points.

• 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.

• Beamwidth Approx

  Approximate the parabolic dish half-power beamwidth in degrees as 70 x lambda / D; wavelength and dish diameter must be positive.

• Antenna Half Power Beamwidth

  Angular separation of the two −3 dB pattern crossings around one antenna main lobe.

• Near Field Distance

  Compute the outer boundary of an aperture antenna's reactive near field as Rn = 0.62 x sqrt(D^3 / lambda); dish diameter and wavelength must be positive.