Quarter-Wave Vertical

Calculate quarter-wave vertical radiator and radial lengths for ham radio frequencies.

A simple vertical radiator with a radial field or ground system. Performance depends as much on the radials as it does on the radiator itself.

Band

Frequency (MHz)

Velocity Factor (%)

Number of Radials

Quarter-Wave Vertical Formula

These are the sizing relationships used by this calculator.

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

Vertical element = lambda / 4

Each radial = lambda / 4

Yes. It calculates both the radiator and radial length using the selected frequency and velocity factor.

Four is a practical minimum, but additional radials usually improve efficiency and reduce ground losses.

Real antennas still depend on environment, conductor diameter, insulation, feed method, and nearby structures. Expect to trim and retune.

Bare wire is commonly near 95%, but different conductors and insulated wire can shift the practical length enough to matter.