**Subject :**Microwave Engineering

## Power transmission in rectangular waveguides

**Introduction :-
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The power transmitted through a waveguide and the power loss in the guide walls can be calculated by means of the complex Poynting theorem .

**Power transmission : -
**

It is assumed that the guide is terminated in such a way that there is no reflection from the receiving end or that the guide is infinitely long compared with the wavelength. From the Poynting theorem ,the power transmitted through a guide is given by :-

For a lossless dielectric, the time-average power flow through a rectangular guide is given by :

For TEmnmodes, the average power transmitted through a rectangular waveguide is given by :

For TMmn modes, the average power transmitted through a rectangular waveguide is given by :

where

is the intrinsic impedance in an unbounded dielectric.