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.

Dipole length (m)

Required number input.

Wavelength (m)

Required number input.

Compute the radiation resistance of a short dipole from its length and wavelength using Rrad = 80 x pi^2 x (l/lambda)^2. 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 resistance (Ω)

The resulting radiation resistance returned as a number.

• 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.

• Effective Length Dipole

  Compute the effective length of a half-wave dipole as lambda divided by pi.

• Effective Aperture

  Compute the antenna effective aperture in square meters as Ae = lambda^2 x G / (4 x pi); wavelength and linear gain must be positive.

• Beamwidth Approx

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