Fully Printed Dual-Layer Depolarizing Chipless RFID Tag for Wearable Applications

work presents a cross-polar dual-layer chipless radio-frequency identification (RFID) tag based on a ladder-shaped resonator design. An integrated ground plane enables direct attachment to human skin without performance deterioration. Simulations show that the ladder-shaped resonator provides several advantages over traditional L-shaped and straight resonators, including a strong cross-polar radar cross section (-23.4 dBsm), third-order harmonics, orientation insensitivity, and compact size (0.062 ?(2)). The effects of the ground plane shape on the surface current distribution are investigated, and a circular tag of 20 mm radius is designed using ladder res-onator groups and frequency shift encoding to provide an active area of 96.45 bits/?(2) and a unit frequency of 6.03 bits/GHz. The tag substrate is three-dimensionally (3D) printed with metallic resonator patterns that are subsequently screen-printed on the substrate. The maximum read range is measured at 40 mm using a cross-shaped, dual-polarized Vivaldi antenna connected to a network analyzer. The measured characteristics in free space are in good agreement with the simulation results, and practi-cal on-body performance tests for the manufactured prototype using simulation and direct measurements indicate that the tag performance remains stable for both free space and on-body cases. The fully printed fabrication process makes the proposed tag design suitable for mass production at a low cost.

Automated summary

This work presents a cross-polar dual-layer chipless RFID tag with a ladder-shaped resonator design. The tag can be directly attached to human skin without performance deterioration due to an integrated ground plane. Simulation results show that the ladder-shaped resonator offers advantages such as a strong cross-polar radar cross section, third-order harmonics, and compact size. A fully printed fabrication process makes the proposed tag design suitable for mass production at a low cost.