SDG Electronicssdgelectronics.co.uk/tools/pcb-calculator/wavelength/

Wavelength

Calculate guided wavelength from frequency or period and the effective dielectric constant.

Inputs

Results update as you change the inputs.

Input method
Signal
MHz
ratio
Wavelength divide

Result

Enter your values to calculate a result.

One complete wave along a trace
One complete wave along a trace

Wavelength is the distance travelled in one cycle. Frequency and effective dielectric constant determine the guided wavelength. The quarter-wave and half-wave results are fractions of this distance.

Illustration only. Not to scale.

Full wavelength

N/A

Full wavelengthN/A
Full wavelengthN/A
FrequencyN/A
PeriodN/A
Method and assumptions

λ = c / (f × √εeff), where c is the speed of light and εeff is the effective dielectric constant of the line.

  • For air, use εeff = 1.
  • For microstrip, εeff is below the substrate Er. Use the impedance calculator to estimate it.
  • For stripline, εeff is normally equal to the substrate Er.

Compare wavelength with trace length

Use full wavelength for a rough physical scale, and λ/4 or λ/10 when checking whether a trace is electrically short. The result is only as good as the effective dielectric constant.