Take the 2-minute tour ×  I know that the magnetic field inside
a circular waveguide is  $B_z=B_0\dfrac{\rho}{R}\left(1-
\dfrac{\rho}{2R}\right)\cos{\phi}\sin{\frac{\pi z}{d}}$  How can
I find the two components of the electric field, $E_\rho,
E_\phi$ that is?  share|improve this question add comment  1
Answer  I have some doubts about your formula. It is my
understanding that radial dependence of fields in circular
waveguides is described by Bessel functions (see, e.g., http://w
ww.eecs.ucf.edu/~tomwu/course/eel6482/notes/20%20Circular%20Wave
guide%20and%20Coaxial%20Line.pdf )  EDIT (04/21/2013) I've just
had a chance to look at Jackson, Classical Electrodynamics, 3rd
ed. (please see @Thanos' comment below) The formula in your
question is indeed approximate - it is used as a trial function
in the variational principle. To find the components of electric
field, you need to use Jackson's formula 8.26a, assuming
$E_z=0$.  share|improve this answer Thank yo very much for your
answer! Actualy, this is exactly the fi