Circular Waveguide Calculator

Enter the radius of the circular waveguide to determine its lower cut-off frequency.


  • Cutoff frequency
Formula for Circular Waveguide Calculator

What is a circular waveguide?

A waveguide is a hollow metallic structure used to transfer high-frequency electromagnetic waves (usually in the microwave range) from one place to another. A waveguide with a circular cross-section is known as a circular waveguide. The circular waveguide supports both TE (transverse electric) and TM (transverse magnetic) modes. In a circular waveguide, TE11 mode is the dominant mode, i.e., at this mode, the electromagnetic wave propagates via the circular waveguide with a minimum loss or minimum degradation. Circular waveguides will only carry or propagate signals above a certain frequency, called the cut-off frequency. The cut-off frequency of the waveguide is inversely proportional to its radius.

They are easier to manufacture and implement than rectangular waveguides since only one dimension, the radius is needed to be maintained. They are used in radio frequency equipment that requires rotation such as a rotary joint in a radar antenna. 

 How to calculate the Cut-off Frequency of circular Waveguides?

The following formula is used to calculate the cut-off frequency of the circular waveguide.


fc = Cutt off Frequency(Hz)

C = Speed of Light(m/s)

r = internal radius for the circular waveguide (m/cm)

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