Millimeter wave radars are employed in a wide range of commercial, military and scientific applications for remote sensing, safety, and measurements. But, radar systems suffer from two major problems such as false images and system-to-system interference. False echoes cause driving hazards. These problems can be eliminated through the use of an EM wave absorber. In this dissertation, the EM wave absorbers using Carbon black as a conductive material, TiO2 as a dielectric material, and Permalloy as a magnetic material with CPE were designed and fabricated for W-band navigation radars. First of all, the complex relative permittivity and permeability of three-type absorbing materials are calculated from the S-parameter. The optimum composition ratios of absorbing materials were determined from absorption ability of various composite. The EM wave absorption abilities at different thicknesses are simulated using material properties of the EM wave absorbers, and the EM wave absorbers were fabricated based on the simulated designs. The simulated and measured results agree very well. As a result, the sheet-type absorbers were developed to eliminate false image and system-to-system interference of navigation radars in W-band.