A Ka dual-band circular waveguide polarizer

The design of a Ka dual-band circular polarizer by inserting a dielectric septum in the middle of the circular waveguide is discussed here. The dielectric septum is located in fixing slots, and by adjusting the dimension of the dual-compensation slots which are built in the orthogonal plane, the phase difference of 90 degrees at the center frequency for the dual-band can be achieved. Furthermore, the. gradual changing structures at both ends of the dielectric septum are built for impedance matching, for both E-x. and E-y polarizations. The simple structure of this kind of polarizer can reduce the influence of manufacturing inaccuracy in the Ka-band. The measured phase difference is within 90 degrees +/- 4.5 degrees for both bands. In addition, the return losses for both E-x and E-y polarizations are better than-15dB.