Polarizer miter bends are used to alter the polarization in overmoded waveguides. For future space debris observation with broadband high power W-band radar sensors these are important transmission line components. A polarizer miter bend uses a grooved mirror as phase grid for polarization. The present paper addresses a suitable design of such a phase grid for broadband high power radar applications within the frequency range from 90GHz to 100GHz. An appropriate parameter combination is found by a parametric study. For reduction of the required amount of calculation a plane wave approximation and unit cell simulations are used. With a suitable parameter combination a cross polarization of Xpol B −26 dB can be achieved within the considered frequency range. This corresponds to a suitable value for radar applications.