Abstract: Apparatus including a conveyor for identifying a plurality of items each of which has a radio frequency transponder. A three dimensional (3D) radio frequency antenna is positioned on one side of the conveyor. The conveyor has a movable part for moving the items into and out of the antenna such that the items when in the antenna are completely surrounded by the antenna. A reader sends interrogation signals to the transponders via the antenna and reads identification information from the transponders. The 3D antenna includes a plurality of coils mounted in a 3D arrangement such as to provide a 3D reading field in which all transponders in the reading field may be interrogated. The 3D antenna also includes noise compensation coils at opposite ends of the reading field to minimize electromagnetic radiation from the antenna and also minimize noise from external sources affecting reading of the transponders.

Abstract: Apparatus including a conveyor for identifying a plurality of items each of which has a radio frequency transponder. A three dimensional (3D) radio frequency antenna is positioned on one side of the conveyor. The conveyor has a movable part for moving the items into and out of the antenna such that the items when in the antenna are completely surrounded by the antenna. A reader sends interrogation signals to the transponders via the antenna and reads identification information from the transponders. The 3D antenna includes a plurality of coils mounted in a 3D arrangement such as to provide a 3D reading field in which all transponders in the reading field may be interrogated. The 3D antenna also includes noise compensation coils at opposite ends of the reading field to minimize electromagnetic radiation from the antenna and also minimize noise from external sources affecting reading of the transponders.

Abstract: A three dimensional (3D) radio frequency antenna is positioned on one side of a conveyor which has a movable part for moving items, each of which has a radio frequency transponder, into and out of the antenna such that the items when in the antenna are completely surrounded by the antenna. The 3D antenna includes a plurality of coils which provide a 3D reading field in which all transponders in the reading field may be interrogated and also includes noise compensation coils at opposite ends of the reading field to minimize electromagnetic radiation from the antenna and also minimize noise from external sources. The radio frequency transponder includes a housing, a substrate within the housing, an integrated circuit and a printed circuit board mounted on the substrate. A coil is mounted on the substrate such as to be spaced therefrom with the spacing of the coil from the substrate enabling the encapsulant to completely surround the coil.

Abstract: In a transponder application, at least one transponder and at least one interrogating reader, the reader has at least two receiving units so disposed, for instance at different distances, relatively to the transponder, that signals from the same are received at different levels by the receiving units. By combination, e.g. by subtraction, of the received signals, disturbing signals received at practically the same level are eliminated while the difference of useful transponder signals is available. This substantially improves system performance in transponder applications and allows to increase the operating distance between reader and transponder.

Abstract: A method for communication with multiple transponders, particularly for reading digital information from transponders. The information being different in every transponder, as may be a chip serial number (S/N), is transmitted by the transponders using the same response channel for all transponders in such a way that possible states of a digital information per digit are transmitted during different windows in time for every digit position using a type of modulation (e.g. ASK, FSK, PSK). Each window is associated to a possible state of a digit position. In one embodiment some of the windows are associated to a predetermined state corresponding to no modulation for reference.

Abstract: In a transponder application comprising at least one transponder and at least one interrogating reader, this reader has at least two receiving units so disposed, for instance at different distances, relatively to the transponder, that signals from the same are received at different levels by the receiving units. By combination, e.g. by subtraction, of the received signals, disturbing signals received at practically the same level are eliminated while the difference of useful transponder signals is available. This substantially improves system performance in transponder applications and allows to increase the operating distance between reader and transponder.