Field and Wave Electromagnetics 2nd Edition by David Cheng

Exercise 27

An air-filled a × b ( b a 2 b ) rectangular waveguide is to be con­structed to operate at 3 (GHz) in the dominant mode. We desire the operating frequency to be at least 20% higher than the cutoff frequency of the dominant mode and also at least 20% below the cutoff frequency of the next higher-order mode.
a) Give a typical design for the dimensions a and b.
b) Calculate for your design , u p , g , and the wave impedance at the operating frequency.