# How are modes classified in rectangular waveguides?

• Roodles01
In summary, the classification of modes in a rectangular waveguide is denoted by two suffix numbers, m and n, which represent the number of half-wavelengths across the width and height of the waveguide, respectively. The EM waves travel through the waveguide, interacting with the walls and experiencing losses due to skin effects. At the boundary, the electric and magnetic fields are typically zero.
Roodles01

## Homework Statement

How do I classify modes? If there is a rectangular waveguide how can I show it is operating in TE10, TE20 or TE11 mode.

## Homework Equations

Could someone help clarify how the 10, 11 or 20 comes about?
Is it due to the dimensions of the guide or something else?

OK Wikipedia has helped.

"In rectangular waveguides, rectangular mode numbers are designated by two suffix numbers attached to the mode type, such as TEmn, where m is the number of half-wavelengths across the width of the waveguide and n is the number of half-wavelengths across the height of the waveguide."

Also realized that the EM waves travel within the cavity, through the dielectric (air) & losses (attenuation) are through interaction with the wall & from skin effects.
Generally at the boundary the electric & magnetic fields are zero.

I'm not quite sure as to why the E & H fields should be zero though, except that when there is no E field, then H will also be zero.

Last edited:

## 1. What are TE modes in EM waveguides?

TE modes, or transverse electric modes, are electromagnetic waves that travel through a waveguide with an electric field perpendicular to the direction of propagation. These modes only have a magnetic field in the direction of propagation, and no electric field in that direction.

## 2. How are TE modes different from TM modes?

TM modes, or transverse magnetic modes, are electromagnetic waves that travel through a waveguide with a magnetic field perpendicular to the direction of propagation. Unlike TE modes, TM modes have no electric field in the direction of propagation and only a magnetic field in that direction.

## 3. What is the cutoff frequency for TE modes?

The cutoff frequency for TE modes in a waveguide is the frequency at which the mode can no longer propagate through the waveguide. This frequency depends on the dimensions and shape of the waveguide, and can be calculated using the waveguide's cutoff wavelength.

## 4. How are TE modes excited in a waveguide?

TE modes can be excited in a waveguide through various means, such as by using a coaxial feed, a slot, or a waveguide aperture. The specific method used depends on the type of waveguide and its dimensions.

## 5. What are some applications of TE modes in EM waveguides?

TE modes in EM waveguides are commonly used in microwave and optical communication systems, as well as in microwave and optical sensors. They are also used in microwave and optical components such as filters, couplers, and switches.

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