Coaxial Cable Wavelength Calculator and Formula

This calculator determines the wavelength of a RF signal inside a coaxial cable based on the signal frequency and the cable’s velocity factor (VF).
When designing an RF system that uses coaxial RF cable, multiply the calculated free space wavelength by the cable’s specified velocity factor to determine the wavelength inside the cable. This value can be used to determine appropriate cable lengths for microwave links, industrial equipment, and satellite installations, including quarter wavelength components and phase aligned connections.
Choose between 50-ohm and 75-ohm cables according to the impedance requirements of the connected equipment, then consider whether flexible or semi-rigid cable better suits the installation.
Before ordering cable by the length or as a completed assembly, review its attenuation specifications at the intended operating frequency to assess its signal loss performance.
The velocity factor is a measure of how much slower the signal travels through the cable compared to free space, typically ranging from 0.6 to 0.9 for common coaxial cables.

Coaxial Cable Wavelength Formula

\lambda_{\text{cable}} = \lambda_{\text{free-space}} \times VF

Where:

The free-space wavelength is calculated as:

\lambda_{\text{free-space}} = c / f

Therefore, the combined formula is as follows:

\lambda_{\text{cable}} = \left(\frac{c}{f}\right) \times VF

Where,

RF wavelength inside coaxial cable formula

Use case : Calculate length of quarter wavelength cable section provided RF signal frequency (100 MHz) and velocity factor (0.66) of coaxial cable is given.

INPUTS:

OUTPUT: