Frequency ↔ Wavelength (with λ/2, λ/4)
Convert between frequency and wavelength and get λ/2 and λ/4 lengths, optionally in a dielectric medium.
Worked example
(Relative permittivity εr 1) Frequency 100 MHz, Wavelength λ 2.99792 m, λ/2 1.49896 m, λ/4 0.749481 m
Formula
λ = c / (f·√εr)
c = 299 792 458 m/s
How it works
Free-space wavelength is λ = c/f and shrinks by √εr in a dielectric. It is the first number to compute when estimating antenna length, slot leakage, PCB trace resonance or cable resonance.
Practical tipA slot or aperture in a shield loses nearly all shielding effectiveness as its longest dimension approaches λ/2. Keeping slots below λ/20 is a common rule of thumb for roughly 20 dB of shielding.
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Results and summaries are for reference. For certification and test reports use the latest official standard text and calibrated instrument data. Last updated: 2026-10-10