Electromagnetic waves carry energy and momentum . So therefore energy of Electromagnetic waves should possible to transfer from one place to another place .
When your working with low frequencies typically less than 200MHz , sending electrical signal through either parallel transmission lines or coaxial cable is fairly common place.
Once the frequency becomes higher we need special convit to send Electromagnetic waves from one place to another place and the method by which we send is known as WAVAGUIDES.
Waveguides are defined as which transfer electromagnetic energy or power from one place to another place.
A waveguide is a special form of transmission line consisting of a hollow, metal tube. The tube wall provides distributed inductance, while the empty space between the tube walls provide distributed capacitance. Waveguides are practical only for signals of extremely high frequency, where the wavelength approaches the cross-sectional dimensions of the waveguide. It conduct microwave energy at lower loss than coaxial cables.
Princle of operation:
Wave propagate in all directions in open space as a spheric al waves. The power of the wave falls with the distance R from the source as the square of the distance( inverse square law). A waveguide confines the wave to propagate in one dimension, so that under ideal conditions, the wave loses no power while propagating. Due to total reflection at the walls , waves are confined to the interior of a waveguide.
What are waveguides ?
- They are devices to transmit electromagnetic power or energy from one place to another.
- For low frequency transmission, one can use parallel transmission lines or coaxial cables. For higher frequencies one used Waveguides.
- Waveguides can be hallow metal tubes or optical fibers.
( Optical fibers are widely using to carry signals from one place to another)
- Waveguides provide an alternative to transmission lines for transmission of electric energy at microwave frequencies.