Microwave waveguides

A waveguide is used to guide an electromagnetic wave. For microwave communication, rectangular or circular shaped metallic tubes are used. Here electric and magnetic fields are confined to the space within the guides. Power loss and dielectric loss are found to be negligible since the guides are air filled. Multimode microwave transmission is possible in waveguides. A rectangular waveguide is a hollow metallic tube with a rectangular cross section. A circular waveguide is a circular conductor in a tubular shape. Other types of waveguides are elliptical waveguides and reentrant waveguides. Microwave cavities are different from microwave waveguides. Cavities are used to store electric and magnetic energies. The commonly used microwave cavities are rectangular cavity resonator, circular cavity resonator and reentrant cavity resonator. Different modes are possible in cavity resonator too and the mode with lowest resonant frequency is known as the dominant mode.