Circular Waveguide: Example

University of Cincinnati-
ECE&CS Department
Microwave Communications
Prepared by: Prof.Altan M. Ferendeci

Circular Waveguide: Example

A circular waveguide of radius r_b cm is connected to a waveguide of radius r_a and then connected back to the circular waveguide of radius r_b. The length of the small diameter waveguide is L=5 cm.

Find the radius r_a that will give an attenuation of 20 dB. The frequancy of the signal is 13.2 GHz.

Given

p₁₁^'=1.841 and k_cr^a=p₁₁^' for the dominant TE₁₁ mode.

Solution:

Attenuation magnitude is calculated from

Using the definition of power attenuation and taking the natural log of both sides, the attenuation constant is found

Uisng the definition of attenuation (for attenuation to take place k_o < k_c), k_c is found first

Finally r_a is equal to

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University of Cincinnati-ECE&CS Department Microwave Communications Prepared by: Prof.Altan M. Ferendeci

Circular Waveguide: Example

University of Cincinnati-
ECE&CS Department
Microwave Communications
Prepared by: Prof.Altan M. Ferendeci