Patent ID: 7564419

Claim:
A composite polarizer comprising: a first polarizer having a plurality of parallel metal vanes, the first polarizer having an axial thickness t 1 , each metal vane having a breadth b 1 , each metal vane separated from an adjacent metal vane by a distance d 1 , the plurality of parallel metal vanes being radially enclosed by a supporting frame, the first polarizer being disposed on an axis, the first polarizer having a phase advance orientation orthogonal to the axis; and a second polarizer having a plurality of parallel layers of dielectric material, the second polarizer having an axial thickness t 2 , each layer of dielectric material having a breadth b 2 , each layer of dielectric material being separated from an adjacent layer of dielectric material by a distance d 2 , the second polarizer being disposed on the axis, the second polarizer having a phase advance orientation orthogonal to the axis, wherein the first polarizer has a first differential phase shift for a first frequency f 1 and a second differential phase shift for a second frequency f 2 , the second polarizer has a first differential phase shift for the first frequency f 1 and a second differential phase shift for the second frequency f 2 , wherein a total of the first differential phase shift of the first polarizer and the first differential phase shift of the second polarizer is about 90°, and wherein a total of the second differential phase shift of the first polarizer and the second differential phase shift of the second polarizer is about 90°.