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Waveguides & Cut-off Frequency Examples

Explain what a waveguide is, the cut-off frequency and give examples in everyday use.

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WAVEGUIDES
A wave propagating in free space spreads out in all spatial directions thus it rapidly decreases in amplitude with distance; this is not good for signal transmission. A waveguide is a way of propagating electromagnetic waves in a particular direction, mainly in the microwave and optical region, without the need for transverse electromagnetic (TEM) modes. This makes them useful for transmission of power and communication signals.
They arise from the superposition of two plane waves, and have a cut-off frequency below which waves will not propagate.
Consider two planes waves travelling at an angle x above and below the z axis. They superimpose to form a travelling wave in the z-direction and a standing wave in the x and y direction. Placing conducting plates along the planes where the tangential electric field is zero does not change the set up and ...

Solution Summary

A wave propagating in free space spreads out in all spatial directions thus it rapidly decreases in amplitude with distance; this is not good for signal transmission. A waveguide is a way of propagating electromagnetic waves in a particular direction, mainly in the microwave and optical region, without the need for transverse electromagnetic (TEM) modes.

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