The step coverage of a dc planar magnetron sputtering system with a revolving substrate is analyzed by both computer simulation and measurement of the step coverage. The model assumes line of sight deposition, no reemission, and the cosine growth law. Good quantitative agreement has been obtained between the model and the experiments. The modeled system does not show the deep cracks typical of the point source planetary system. This is explained by comparing the vapor distribution functions of the planetary and the sputtering systems.