6. What is a waveguide. Explain?

Friday, 21 February 2014

6. What is a waveguide. Explain?


A wave-guide is a hollow conducting pipe, of uniform cross-section, used to transport high frequency electromagnetic waves (generally, in the microwave band) from one point to another. The main advantage of wave-guides is their relatively low level of radiation losses (since the electric and magnetic fields are completely enclosed by a conducting wall) compared to transmission lines.

Also waveguide can be any medium that support the transmission or propagation of electromagnetic wave, so microwave waveguides can be a co-axial conductor, parallel plates and the above said hollow single conductor.And the term waveguides are generally used for these hollow conducting pipes.

Usually hollow waveguides are manufactured using brass, bronze, aluminium. Some times the inner surface is coated with silver or gold to avoid ohmic losses at high frequencies.

The hollow waveguides can take any shape of cross section but commonly seen are

Rectangular

Circular

Elliptical

Depending upon the shape and dimensions of the waveguide there is a cut off frequency of transmission. Only the waves having frequency greater than cut off frequency (fc) will be propagated. Hence waveguides act as a high pass filter with cut off frequency fc.

Also a TEM wave cannot be propagated through a hollow waveguide.


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