An embodiment of the invention relates to systems and methods for detecting the orientation of sample carriers using two or more RFID tags. One or two dimensional matrix of equally spaced RFID reader antennas may be positioned beneath or within an area on which racks are placed. The first RFID tag defines the origin of the sample carrier and its geometry. The second and additional RFID tags define the orientations of the sample carrier relative to the matrix of the RFID reader antennas. At least two of the tag antennas on the rack align uniquely with two antennas on the reader matrix. The system energizes each reader antenna and associates the RFID tags aligned with them to the RFID reader antenna's physical position.