Sender eines Reifenzustandsüberwachungsgerätes und Reifenzustandsüberwachungsgerät

A transmitter (30) of a tire condition monitoring apparatus (1) wirelessly transmits transmission data containing air pressure data of a tire (20). The wireless transmission of the transmission data is performed when a reception antennal (35) in the transmitter receives a trigger signal transmitted by an initiator (60). The reception antenna is arranged relative to the tire such that the orientation of the directivity of the reception antenna is constant irrespective of a rotation angle of the tire. Therefore, the transmitter operates reliably irrespective of the rotation angle of the tire.