Question

A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls calculate the phase velocity for dominant mode.

Answer 1

Answer

Relationship between group and phase velocity

$v_pv_g=c^2$

So phase velocity is given by

$v_p=\frac{c}{\sqrt{1-(\frac{f_c}{f}) ^2}}$

Putting all given value in question

$c=3\times10^8 m/s$

And all other

$v_p=5\times10^8m/s$