A device (110) for evaluating an electromagnetic field strength/field geometry of an electromagnetic gate apparatus (120) is provided, the device (110) comprising a measurement unit (112) adapted for receiving a measurement signal from the electromagnetic gate apparatus (120) and determining a value of the field strength of said measurement signal, a communication unit (114) adapted for receiving command data from the electromagnetic gate apparatus (120) and adapted for sending response datato the electromagnetic gate apparatus (120). Optionally, the device (110) comprises an evaluation unit (116,118) adapted for evaluating the electromagnetic field geometry of the electromagnetic gate apparatus (120) based on said values of the field strength received from the measurement unit (112).