Mobile radio reception, in particular in motor vehicles, has the disadvantage in comparison to geographically fixed home reception, that line of sight contact with the transmitter rarely exists and the signal strength near the ground is significantly smaller than the signal strength for roof-top antennas. For minimizing these disturbances, antenna diversity systems were developed. A practical problem in the realization of antenna diversity systems is comprised therein, that the diversity circuits do not support a targeted selection of individual antennas so that the individual antennas following installation can be tested for their functionality. Proposed is a process and a diagnostic device for selective testing of receiver antennas in a multi antenna system (6), which is controlled by a diversity circuit (10) and is couplable and/or coupled with a receiver (8), therein the receiver antennas are irradiated with a test signal (17), which exhibits a first signal progression segment, which brings about a reswitching of the receiver antenna by the diversity circuit (10) and includes a second signal progression segment which impedes a reselection or switching of the receiver antenna by the diversity circuit (10).