The knowledge of characteristic parameters of a radar as well as of the radiation pattern of its associated antenna array is of fundamental importance for the analysis and comparability of radar observations. Some parameters can be measured directly at the radar, others need to be derived indirectly. For example, the radiation pattern, the phase distribution of antenna-receiver combinations and the receiver dynamic range and bandwidth need to be known and optimized. Here, active and passive experiments as well as hardware measurements are used for the calibration and validation of the radar.