Waveguide Calculator

A rectangular waveguide is a hollow metal tube used to carry microwave signals — its physical dimensions determine which frequencies it can transmit. Enter your broad wall width (a), narrow wall width (b), operating frequency, and TE mode (m, n) into the Waveguide Calculator to find the cutoff frequency for your selected mode. Secondary outputs include guide wavelength, wave impedance, and attenuation constant.

mm

Width of the larger dimension of the waveguide

mm

Width of the smaller dimension of the waveguide

GHz

Frequency at which the waveguide will operate

Mode number in the x-direction

Mode number in the y-direction

Results

Cutoff Frequency

--

Guide Wavelength

--

Wave Impedance

--

Attenuation Constant

--

More Electrical & Electronics Tools

Frequently Asked Questions

What is the cutoff frequency in rectangular waveguides?

The cutoff frequency is the minimum frequency required for a specific TE or TM mode to propagate through the waveguide. Below this frequency, the mode is evanescent and cannot propagate.

What is the dominant mode in rectangular waveguides?

The dominant mode in rectangular waveguides is TE10, which has the lowest cutoff frequency. This mode is most commonly used in practical applications because it can propagate at the lowest frequency.

How do waveguide dimensions affect cutoff frequency?

The cutoff frequency is inversely proportional to the waveguide dimensions. Larger dimensions result in lower cutoff frequencies, while smaller dimensions increase the cutoff frequency.

What happens when the operating frequency is below cutoff?

When the operating frequency is below the cutoff frequency, the electromagnetic wave cannot propagate and is rapidly attenuated. The mode becomes evanescent and decays exponentially along the waveguide.

How is guide wavelength different from free space wavelength?

Guide wavelength is always longer than the free space wavelength at the same frequency. It represents the distance between two points of equal phase along the waveguide and depends on both frequency and waveguide dimensions.

What is wave impedance in waveguides?

Wave impedance is the ratio of transverse electric field to transverse magnetic field in the waveguide. It varies with frequency and is different from the characteristic impedance of transmission lines.

Why are rectangular waveguides preferred over circular ones?

Rectangular waveguides are easier to manufacture, have better mechanical stability, and allow for simpler coupling mechanisms. They also have well-defined polarization and no degenerate modes in the dominant TE10 mode.