FC       – Cutoff Frequency

λCutoff – Wavelength at FC

λGuide – Guide wavelength

A Rectangular Waveguide is a conducting cylinder of rectangular cross-section used to guide the propagation of waves. A rectangular waveguide is commonly used for the transport of radio frequency signals.

The cutoff frequency is the frequency up to which the system functions efficiently. Below the cutoff frequency, power flow will be reduced. In the waveguide, the cutoff frequency is the frequency up to which EM mode will propagate easily. Below this frequency waveguide will attenuate the EM mode and will not be suitable for electromagnetic wave propagation.