the invention relates to a method and monitoring means for monitoring the performance of an antenna device . in the prior art the monitoring of the performance of antenna systems , in particular of antenna systems of base stations , has been done by monitoring systems comparing actually measured performance samples with common and fixed alarm threshold values which shall be valid for many antenna systems but which were not adapted to individual antenna device installations . in order to achieve more reliable alarms with less costs the present invention proposes to detect a deterioration in the performance of the antenna device by watching and evaluating the variation of different performance samples taken from time to time from said antenna device .