# Solved Problems-13

Problem-13

An air-filled rectangular waveguide of 5 cm Ã— 2 cm cross section is operating in the

*TE*_{10}mode at a frequency of 4 GHz. Determine- the group velocity
- the guide wavelength
- the attenuation to be expected at a frequency which is 0.95 times the cut-off frequency (assuming the guide walls to be made of perfect conductors)

Solution

Here,
The cut-off frequency is given as,
The group velocity is given as,
The guide wavelength is given as,
For attenuation, the operating frequency is,
The propagation constant is given as,
Since, the propagation is purely real, the attenuation constant is 19.62 Np/m

*a*= 5 cm,*b*= 2 cm,*f*= 4 GHz,*m*= 1,*n*= 0