📏 Half‑Wave Dipole Length Calculator

A half‑wave dipole is resonant when its length is approximately half the wavelength. The classic formula is L = 0.5 × λ, but due to end effects, a more accurate formula is L (m) = 143 / f (MHz) for wire dipoles.

Input

Frequency (MHz): Wavelength (m):

Dipole Length

1.43 m

Approximate length for a half‑wave dipole (using L = 143 / f).

Formula: L (m) = 143 / f (MHz) (for bare wire dipole in free space).
Derivation: λ = c / f, half‑wave = λ/2 = 150 / f (MHz) if c = 3×10⁸ m/s. The empirical factor 143 accounts for the velocity factor of a thin wire.

← Back to calculators