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 90deg 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 90degplusmn 4.5deg for both bands. In addition, the return losses for both E_x and E_y polarizations are better than -15 dB.