Waveguides

Today we shall concentrate on one of the Transmission media called wave guides. A hollow conducting tube to transmit electromagnetic waves is termed as wave guide. A waveguide is a hollow tube designed to carry microwave energy from one place to another place. Waveguides may be used to carry energy between pieces of equipment or over longer distances. Waveguides are made from copper, aluminum or brass. These metals are extruded into long rectangular or circular pipe

The electric and magnetic fields of electromagnetic wave are confined to the space within the guide and made to propagate down the length of the wave guide.

Characters of waveguides:

• The propagation takes place through the dielectric field.
• Propagation is in terms of electric and magnetic fields rather than voltage and currents.
• The electric and magnetic fields that exist inside the waveguide are solution of Maxwell’s wave equation.
• Each waveguide has cut off frequency that decides the dominant mode of propagation.

Coming to the types of waveguides. There are three types of waveguides namely:

1. Rectangular waveguide:

     2.circular (cylindrical) waveguide:

     3.Ridged waveguide:

Advantages of waveguides:

• The waveguides can be used at much higher frequencies than the co-axial cables.
• Easy to manufacture than co-axial cable because waveguides are hollow.
• Waveguides do not have either inner conductor or dielectric material, therefore power handling ability is improved. It is about 10 times as high as for co-axial air dielectric rigid cables.
• Power losses are less.
• There is no radiation loss.

Applications:

• They are at their supreme in microwave transmission.
• Used to connect Radar transmitter to antenna.
• Used to channel the received echo to the receiver from the antenna