Waveguide Cutoff Frequency

A waveguide is a hollow metal tube (with a rectangular or circular cross-section) that transmits electromagnetic energy from one port to another. The cut-off frequency of a waveguide is the frequency above which signals will propagate through it with minimal attenuation. This means that signals with a frequency above the cut-off frequency will propagate through a waveguide and signals below this frequency will be attenuated.

The cut-off frequency depends on the shape and size of the cross-section of the waveguide. The larger the waveguide, the lower its cut-off frequency.

Cut-off frequency of a Rectangular Waveguide:

Cut-off frequency of a waveguide with a circular cross-section and radius ‘a’: