Tools you might need next
Calculate half-wave dipole and quarter-wave vertical antenna element length from frequency. Includes velocity factor correction for wire type.
Calculate LC tank circuit resonant frequency from inductance and capacitance. Q factor and impedance at resonance for RF design.
Calculate Standing Wave Ratio from forward and reflected power readings. Convert SWR to return loss and reflected power percentage.
Speed of light (3×10⁸ m/s) divided by frequency. 7 MHz → 42.86 meters. Free space approximation.
λ (m) = 300 ÷ f (MHz)Reverse calculation. A 20-meter band wavelength corresponds to approximately 15 MHz (actually 14.0–14.35 MHz band).
f (MHz) = 300 ÷ λ (m)Imperial formula for antenna calculations. 14 MHz → 70.3 feet full wavelength.
λ (ft) = 984 ÷ f (MHz)Updated: July 2026
20-meter wavelength = 300 ÷ 14.2 ≈ 21.1 meters. Band name corresponds to approximate wavelength in meters.
Director spacing at 0.15λ on 144 MHz: λ = 2.08m, spacing = 0.31m (12.2 inches) between elements.
At 1.8 MHz (160m), wavelength 166m — ground wave propagation dominant. At 28 MHz, 10.7m wavelength enables sporadic-E skip.
Frequency and wavelength are inversely related through the speed of light. Enter frequency in MHz or wavelength in meters to convert between units for antenna design, propagation analysis, and frequency-to-band identification.