Frequency & Wavelength
Enter frequency, wavelength or period and get the others, in vacuum or in a medium with its velocity factor (coax, fiber). The basis for antennas, cables and RF.
All quantities
| Quantity | Value | Formula |
|---|
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How it is computed · f, λ, T and antennas
1. In vacuum waves travel at
c = 299,792,458 m/s. In a medium the speed drops:
v = VF · c, where VF is the velocity factor
(coax ≈ 0.66–0.85; fiber ≈ 0.68 from n ≈ 1.47).
2. Frequency and wavelength are inverse:
λ = v / f and f = v / λ. The period is
T = 1 / f.
3. For antennas: λ/4 (a quarter
wave) gives the length of a monopole or a stub; λ/2 is a
dipole. Use the λ of the element's medium (with its VF).
4. Example: 2.4 GHz in vacuum →
λ = 3·10⁸ / 2.4·10⁹ ≈ 12.49 cm, T ≈ 0.417 ns and
λ/4 ≈ 3.12 cm.
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How it works
The converter takes a single input (frequency, wavelength or period, in the unit you choose: Hz to THz, nm to m, ps to s) and computes the other two, plus the quarter wave (λ/4) and half wave (λ/2) used to size monopoles, stubs and dipoles. You can work in a vacuum or inside a medium by entering its velocity factor (VF): RG-58 coax ≈ 0.66, LMR-400 ≈ 0.85, optical fiber ≈ 0.68.
The formulas are the standard wave-propagation ones: the speed in the medium is v = VF · c with c = 299,792,458 m/s, the wavelength is λ = v / f, the frequency f = v / λ and the period T = 1 / f. Results are shown with the most convenient SI prefix (GHz, cm, ns) and also in a table with the formula used for each quantity.
Example: how long is the 2.4 GHz WiFi wave?
- In a vacuum (VF = 1) the speed is
c = 299,792,458 m/s. - Wavelength:
λ = c / f = 299,792,458 / 2.4·10⁹ ≈ 12.49 cm. - Period:
T = 1 / f ≈ 0.417 ns; quarter wave: λ/4 ≈ 3.12 cm (typical length of a 2.4 GHz monopole).