An alarm pane assembly is presented. The alarm pane assembly includes a pane made of tempered glass, a transparent, electrically conductive coating that is arranged on a surface of the pane, a sensor unit, and an antenna. According to one aspect, the sensor unit includes a transmitting unit and an evaluation unit. During operation, the transmitting unit forwards a high-frequency voltage signal with a frequency f in a range of 0.1 GHz to 6 GHz to the antenna, the antenna emits electromagnetic radiation of the frequency f, and the evaluation unit measures the impedance matching of the transmitting unit to the antenna. According to another aspect, the antenna is electromagnetically coupled to the conductive coating, and the sensor unit outputs an alarm signal when the measured impedance matching deviates from a reference value.