Calibration-Free Chipless Radiofrequency Identification Tags with Enhanced Data Capacity

System Development of Calibration-Free 20.7-Bit Chipless RFID Without Iterative Optimization of Tag Configurations

“…Table 1 also presents the data capacity, the design technique of tags, and the evaluation scheme of experimental results. Only two studies demonstrate capacity greater than 16 bits [15], [19]. While the multicarrier detection scheme has a maximum achievable capacity of 37 bits, the prototype validates the concept by a 4-bit system [20].…”

“…While the multicarrier detection scheme has a maximum achievable capacity of 37 bits, the prototype validates the concept by a 4-bit system [20]. When the number of ID combinations is as high as thousands [19], millions [15], or even billions [20], converting all the IDs to tag geometry requires significant time and efforts, if the tags are designed by iterative tuning. For example, the calibrationfree tag has been developed by 16 dipole arrays backed with conductor [19].…”

“…The reader signal processing employs STFT featuring enhanced filtering. While STFT has been considered as an effective calibration-free technique [10]- [15], the algorithm implemented in this system comprises the standard STFT operation, time gating, and the enhanced filtering on time-frequency spectrograms.…”

“…In particular, the characteristics of earlier calibration-free techniques are summarized in Table 1 [10]- [20]. Most of the calibration-free detections feature short-time Fourier transform (STFT) for backscattering signals [10]- [15]. To improve the timefrequency windowing resolution, several schemes are integrated to STFT, such as enhanced filtering [10] and matrix pencil methods (MPM) [13], [14].…”

“…The goal of this paper is to develop a high-capacity and calibration-free system without performing iterative optimization for the tags. In addition to our preliminary study that encodes 22.1 bits only in simulation [15], this paper constructs the highest overall data capacity with calibration-free detection; more importantly, the tags are designed by the noniterative synthesis. 1.68 million tags can be determined by mathematical expressions, instead of iterative full-wave simulation.…”