Wavelength and Frequency Calculator
Convert between radio frequency and wavelength.
Calculate quarter-wave and half-wave antenna dimensions for any amateur radio band.
Wavelength and Antenna Dimensions
The relationship between frequency and wavelength is fundamental to all radio antenna design.
Formula: λ = c / f
Where λ is wavelength (meters), c is the speed of light (299,792,458 m/s ≈ 300 Mhz·m), and f is frequency in Hz.
Simplified: λ (meters) = 300 / f (MHz)
Common antenna dimensions:
- Full wavelength: λ = 300 / f(MHz)
- Half-wave dipole (free space): λ/2 = 150 / f(MHz)
- Half-wave dipole (wire, velocity factor 0.95): 142.5 / f(MHz)
- Quarter-wave vertical: λ/4 = 75 / f(MHz)
Amateur radio band wavelengths:
- 160 m band: 1.8–2.0 MHz, λ = 150–167 m
- 80 m band: 3.5–4.0 MHz, λ = 75–86 m
- 40 m band: 7.0–7.3 MHz, λ = 41–43 m
- 20 m band: 14.0–14.35 MHz, λ = 20.9–21.4 m
- 15 m band: 21.0–21.45 MHz, λ = 14.0–14.3 m
- 10 m band: 28.0–29.7 MHz, λ = 10.1–10.7 m
- 2 m band: 144–148 MHz, λ = 2.03–2.08 m
- 70 cm band: 420–450 MHz, λ = 0.667–0.714 m
Velocity factor in coaxial cable is typically 0.66–0.80, meaning the electrical wavelength inside coax is shorter than in free space. This matters for designing coaxial stubs and phased arrays.