Recent Advances in Electromagnetic Encoders for Motion Sensing and Chipless-RFID

This paper reviews the recent advances in electromagnetic encoders for motion sensing and near-field chipless-RFID. The reported encoders exhibit more than one bit of information per encoder position (or row), and the main target in the research activity carried out by the authors has been to maximize such number of bits per encoder position, a Figure of Merit (FoM), as much as possible. It is shown that, for that purpose, it is necessary to encode not only in time (the former procedure), but also in frequency, in phase, or in frequency and phase simultaneously. Various prototype examples are reported in the paper. The highest achieved FoM is 8.78 bits per encoder position.