In this thesis, we investigate the transformation bandwidth and the thickness sensitivity of the anisotropic-slab linearly polarizes (LP) to circularly polarized (CP) polarizer. We define a transformation bandwidth and the thickness sensitivity based on the axial ratio. New methods are proposed that can eliminate the lengthy derivation and give deeper physical insight to the problem. Under the small reflection approximation, i.e., only the forward waves are considered, our methods can be applied to the design of the anisotropic-slab LP to CP polarizer. For the single anisotropic slab, the effect is represented graphically on the polarization ratio plane. It is shown that the polarization locus for a given axial ratio leads to a circle in the polarization state diagram. When combined with the graphical description of the change in the polarization state, the transformation bandwidth and the thickness sensitivity from an initial LP wave to a desired CP wave can be obtained easily. Furthermore, we present a method using the equivalent circuits to represent the polarization effect in anisotropic media, so that some concepts of the electric circuit can be applied. This method is more convenient in dealing with the polarization change when multiple anisotropic-slabs exist. The transformation bandwidths and the thickness sensitivities for the anisotropic-slab polarizer for several lossless media are studied. The results are discussed and illustrated.