An antenna system (2a-d) for determining a transit of a movable object through a detection area within a detection plane, the antenna system (2a-d) comprising: an exciter loop antenna spanning the detection plane and configured to provide an exciting electromagnetic field, wherein the exciting electromagnetic field or at least one spatial component thereof perpendicular to the detection plane has a field strength above a field strength threshold in the detection area, wherein the exciting electromagnetic field is capable of exciting the movable object to emit an electromagnetic response signal (44a, 44b) comprising information on a position of the movable object, wherein the exciter loop antenna comprises, within the excitation signal path of the exciter loop antenna, a closed loop path (30a; 30b) formed between a first terminal and a second terminal on the excitation signal path, wherein an excitation signal travels from the first to the second terminal via a first signal path and a different second signal path forming the closed loop path (30a; 30b), wherein the closed loop path (30a; 30b) spans a sensor antenna plane perpendicular to the detection plane; and a sensor loop antenna (4a-d; 4b', 4c') comprising a magnetic core having a longitudinal axis perpendicular to the sensor antenna plane for receiving the electromagnetic response signal (44a, 44b), wherein the magnetic core is positioned in between the first and the second signal path (30a; 30b) within a predefined area around an intersection of the detection plane and the sensor antenna plane, the predefined area forming a region of the exciting electromagnetic field where the field strength of the exciting electromagnetic field or at least one spatial component thereof parallel to the longitudinal axis of the magnetic core is below said field strength threshold. an exciter loop antenna spanning the detection plane and configured to provide an exciting electromagnetic field, wherein the exciting electromagnetic field or at least one spatial component thereof perpendicular to the detection plane has a field strength above a field strength threshold in the detection area, wherein the exciting electromagnetic field is capable of exciting the movable object to emit an electromagnetic response signal (44a, 44b) comprising information on a position of the movable object, wherein the exciter loop antenna comprises, within the excitation signal path of the exciter loop antenna, a closed loop path (30a; 30b) formed between a first terminal and a second terminal on the excitation signal path, wherein an excitation signal travels from the first to the second terminal via a first signal path and a different second signal path forming the closed loop path (30a; 30b), wherein the closed loop path (30a; 30b) spans a sensor antenna plane perpendicular to the detection plane; and a sensor loop antenna (4a-d; 4b', 4c') comprising a magnetic core having a longitudinal axis perpendicular to the sensor antenna plane for receiving the electromagnetic response signal (44a, 44b), wherein the magnetic core is positioned in between the first and the second signal path (30a; 30b) within a predefined area around an intersection of the detection plane and the sensor antenna plane, the predefined area forming a region of the exciting electromagnetic field where the field strength of the exciting electromagnetic field or at least one spatial component thereof parallel to the longitudinal axis of the magnetic core is below said field strength threshold.