The developed prototype has proved to be a useful instrument for the calibration of Doppler/range radars. The system includes innovative solutions for the generation of Doppler and distances with high precision. It is able to generate accurate Doppler shifts with a resolution higher than 4·10^-3 Hz and speeds with an accuracy of around ±2.76 ppm - from 1000 independent measurements - at slant-ranges from 100 meters to 11 kilometers. It can be used with several types of radars in S- and X-band in large dynamic range from miliwatts to several hundreds of Watts. The system has proved very effective in radar calibrations and is being used for the improvement of accuracy and resolution of FM-CW radar systems.