Field and Wave Electromagnetics 2nd Edition by David Cheng

Exercise 40

For a parallel-plate waveguide,
a) find the frequency (in terms of the cutoff frequency f c ) at which the attenuation constant due to conductor losses for the TM„ mode is a minimum,
b) obtain the formula for this minimum attenuation constant,
c) calculate this minimum c for the TM 1 mode if the parallel plates are made of copper and spaced 5 (cm) apart in air.