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.

Frequency (Hz)

Operating frequency of the antenna.

Velocity factor

Ratio of propagation speed in the surrounding medium or insulation to the speed of light, between zero and one.

Compute the quarter-wave element length L = c / (4 * f), optionally shortened by an insulation velocity factor; bare wire in free space uses a factor of one. 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]

Element length (m)

Physical length of the quarter-wave element.

• 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.

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