To allow antenna movements in azimuth and elevation in high-power radar applications, rotary joints are essential. They allow the rotation of a transmission line and therefore are important transmission line components. In the present paper a broadband rotary joint concept for high-power W - band radar applications is proposed. To avoid a twist of the polarization plane of a linearly polarized mode, like HE_11, a combination of two broadband polarizer is used. A cross polarization of X_pol≤ - 20 dB can be achieved within the frequency range from 90 GHz to 100 GHz. This corresponds to a suitable value for radar applications.