In this paper the dominant modes （quasi TE11mode） in circular waveguides filled completely or partially with tangentially magnetized ferrite are studied for the general case-the diagonal components of permeability tensor μr =μz≠μθ. It is found that the characteristic equations for right hand and left hand circularly polarized waves are identical. Consequently

there exists no difference between the propagation constants of these waves

the rotation of plane of polarization is absent when a linearly polarized wave travels through the waveguides. We conclude that these waveguides can be used as polarization insensitive phase shifters and the results of the reference[3

7]（the propagation constants for right hand and left hand circularly polarized waves in these waveguides are different and when a linearly polarized wave travels through the waveguides the plane of polarization is rotated） are questionable.