A Novel Co/Cross-Polarizing Chipless RFID Tags for High Coding Capacity and Robust Detection

The aim of this work is to introduce a novel tag design enhancing the coding efficiency for the Frequency Coded (FC) chipless RFID system. The proposed approach relies on exploiting the backscattered co/cross-polarized signals from a tag excited with a linear-polarized wave. Consequently, the tag signature is encoded into Notch/Peak (N/P) format in two orthogonal planes. Furthermore, the introduced tag design exhibits narrow resonance bandwidth ensuring best utilization of the operating frequency range and sufficient coding capacity with compact tag size. Hence, 80-bit coding capacity is reached employing physical amplitude On Off-N/P (OO-N/P) modulation and N/P-Position (N/P-P) modulation principles. The presence or absence of a resonator resembles the OO-N/P modulation while the shift in the frequency position imitates the (N/P-P) modulation. In addition, the depolarization property increases the probability of tag detection in a real-world heavily dense multi-path environment. An asymmetry crossed dipole structure is employed to facilitate coding in both divergent polarities separately. The manufactured tags are verified in indoor real-world environment to proof the robustness of the introduced tag design and encoding algorithm. In the full paper, various parameters such as reading range, tag miniaturization and angular stability will be investigated.