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Calculators / RF Wavelength
RF Wavelength
Calculator
The fundamental equation of RF engineering: λ = c / f. Calculate wavelength from frequency, or frequency from wavelength — for antenna design, RF engineering, and microwave systems. Covers the full spectrum from ELF to mmWave.
RF Spectrum Position
ELF/VLFAMHFVHFUHFSHFmmWave
⚙ Wavelength Engine
Enter frequency to calculate wavelength
Enter wavelength to calculate frequency
λ in medium = λ₀ / √εr
1.0 = free space. Coax ≈ 0.66–0.85. Overrides medium if <1.0
Advanced Parameters
λ_medium = λ₀ / √εr. Overrides medium selector
°C
Speed of sound in air: c_sound ≈ 331 + 0.6T m/s
m/s
Default: 299,792,458 m/s (exact, NIST)
Total length = n × λ (useful for array design)
Calculated Results
Free-space Wavelength (λ₀)
—m
λ in medium—
Frequency—
λ/2 (half-wave)—
λ/4 (quarter-wave)—
λ in mm—
λ in cm—
λ in inches—
λ in feet—
n × λ (total)—
RF Band—
Period (T = 1/f)—
Wave number (k)—
Enter frequency above to calculate.
📖 Theory
The wavelength is the distance between two consecutive peaks (or any two identical points) of an electromagnetic wave. It is inversely proportional to frequency.
Free-space Formula
λ = c / f
c = 299,792,458 m/s (speed of light), f = frequency in Hz
In a Medium
λ_medium = λ₀ / √εr
λ_medium = λ₀ × k
εr = relative permittivity, k = velocity factor (0–1)
Antenna Length Rule
λ/2 dipole: L ≈ 143/f(MHz) m
λ/4 monopole: L ≈ 71.5/f(MHz) m
Includes VF=0.95 and end-effect corrections.
The wave number k = 2π/λ describes spatial frequency. The period T = 1/f is the time for one complete cycle. Both are fundamental in EM field analysis and transmission line theory.
📡 Wavelength & Spectrum Viewer
Live Simulation
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◉ Wave scales with frequency & medium
Display Mode
Frequency
144 MHz
Medium εr
1.0
Air (1.0)Alumina (12)
Sine Wave (E-field)
ℹ
Wavelength Insights
Enter a frequency above to see wavelength insights.
Common Applications
Antenna Design
Every antenna element length — dipole, monopole, Yagi, patch — is a fraction of λ. Wavelength is the starting point of all antenna design.
RF Engineering
Transmission line stubs, matching networks, quarter-wave transformers, and waveguide cutoff frequencies all depend on λ at the operating frequency.
Microwave Systems
At GHz frequencies, wavelengths are millimetres. PCB trace lengths, via spacing, and component placement all interact with the signal wavelength.
Education
The λ = c/f equation is the most fundamental relationship in RF and electromagnetic engineering — the first equation every RF engineer learns.
Use this result with related RF tools
Wavelength is the starting unit behind many antenna dimensions and propagation calculations. Use free-space wavelength for a first estimate, then account for the medium, substrate, and physical construction where they apply.
Get "10 RF Design Principles Every Engineer Should Know" Free
Learn practical principles for better RF circuits, PCB layouts, simulations, measurements, and troubleshooting.