Parallel plate septum polarizer for low profile antenna applications

4 A parallel plate waveguide septum polarizer in which a pair of waves propagates in orthogonal modes and a third undesired wave also propagates, said polarizer comprising:

• a) a first relatively thin parallel plate waveguide allowing for the propagation of a waveguide mode;
• b) a second relatively thin parallel plate waveguide also allowing for propagation of a waveguide mode;
• c) the modes in the first and second waveguides having the same field structure, wave velocity and impedance;
• d) a third parallel plate waveguide, being wider than either of the first and second waveguides, and where the wide waveguide is fed from the first and second relatively thin waveguides;
• e) the third waveguide allowing for the propagation of three different waveguide modes, two of which are orthogonal but which have different field structures;
• f) the mode in the first waveguide couples most or all of its power to the two desired modes in the third waveguide and couples minimally to the undesired waveguide mode in the third waveguide and to the mode in the second waveguide;
• and
• g) the mode in the second waveguide couples most or all of its power to the two desired modes in the third waveguide and couples minimally to the undesired mode in the third waveguide and to the mode in the first waveguide.