OCF Dipole Calculator

Calculate off-center-fed dipole element lengths and feed-point split for ham radio bands.

Off-Center Fed Dipole

A Windom-style multi-band dipole fed away from center. Common feed points are 33% and 43% from one end, usually with a 4:1 or 6:1 balun.

OCF Dipole Formula

These are the sizing relationships used by this calculator.

Wavelength

lambda (m) = 299.792458 / f(MHz) * VF

Total Length

Total length = lambda / 2

Leg Lengths

Short leg = Total length * Feed point ratio; Long leg = Total length * (1 - Feed point ratio)

FAQ

What feed-point options does this OCF dipole calculator support?

It supports the common 33 percent and 43 percent feed-point positions used for Windom-style multi-band dipoles.

Does an OCF dipole still need tuning?

Yes. The calculated lengths are a starting point. Feed-line routing, height, conductor type, and balun choice still affect the final result.