It is important to inspect the polarization on the plane where a symmetry plane feature is applied. The symmetry plane enforces a PEC or PMC condition and thereby suppresses the tangential field component of electric field or magnetic field on the plane, respectively. Some waveguides modes cannot be simplified using symmetry plane features. For instance, a Zero tangential magnetic field (PMC) symmetry plane cut at the center of a TE20 rectangular waveguide mode can satisfy the boundary condition of the transverse electric field on a port boundary. However, the longitudinal magnetic field component in the waveguide is incorrectly suppressed by the symmetry plane.