Enter any frequency manually or choose
one of the presets below.
📶 Frequency presets
Presets are convenient starting points.
Always use frequencies permitted for
your location and licence.
📐 Antenna settings
Examples: 0.25 = ¼ wave,
0.5 = ½ wave,
1 = full wave.
1.00 = theoretical free-space
length.
ESTIMATED ANTENNA LENGTH
—
Enter a frequency and choose an
antenna type.
WAVELENGTH
—
ANTENNA LENGTH
—
CENTIMETRES
—
MILLIMETRES
—
FEET
—
FEET & INCHES
—
EACH DIPOLE LEG
—
FREQUENCY
—
DIPOLE ELEMENT
Each side is half of the
calculated dipole length.
Starting estimate:
Real antenna resonance can be affected
by conductor diameter, insulation,
mounting height, nearby objects,
ground conditions, feed arrangement
and other environmental factors.
Practical antennas may require final
trimming or tuning.
How the antenna calculator works
Radio waves travel through free space at
approximately the speed of light.
The basic wavelength calculation is:
Wavelength = speed of light ÷ frequency
The calculator then multiplies that
wavelength by the selected antenna
fraction.
¼-Wave monopole
A quarter-wave element is approximately
one quarter of the wavelength before
applying the selected shortening factor.
½-Wave dipole
A half-wave dipole has two elements.
The displayed antenna length is the
approximate overall tip-to-tip length,
and the calculator also gives the
approximate length of
each dipole leg.
⅝-Wave
A five-eighths-wave element is calculated
as 0.625 of the wavelength before applying
the shortening factor.
Full-wave
A full-wave result uses one complete
wavelength before applying the selected
factor.
Shortening factor
The shortening factor lets you reduce the
theoretical free-space dimension.
A value of
1.00
gives the mathematical wavelength
fraction without shortening.
The default
0.95
provides a general starting estimate,
but the appropriate value depends on the
antenna design and materials.
📻 Frequency & installation note
The frequency presets are provided as
convenient calculation examples.
Frequency allocations, licence conditions,
permitted power levels and operating rules
differ by country and service.
Always check the rules that apply where
the radio equipment will be used.
Antennas should also be installed safely
and kept well clear of overhead electrical
power lines.