Using a hybrid encoding method based on the hexagonal resonators to increase the coding capacity of chipless <scp>RFID</scp> tags
Mohsen Hayati, Sohrab Majidifar, Seyed Naeim Sobhani
Abstract
A chipless RFID tag was designed using two hexagonal resonators. By defining a relation for the phases of S-parameters and rotating the resonators around their axes, a senary coding scheme was obtained at the resonant frequency. The designed resonator was able to generate six different codes using six different phase parameters at 3.03 GHz. While the conventional binary (“0” and “1”) coding of ordinary tags makes minimal use of bandwidth capacity, the senary coding in the proposed design allowed the use of a larger bandwidth capacity. Requiring much fewer resonators for generating more codes, the proposed technique leads to significantly smaller tags. Using the proposed tag with two resonators, 62 = 36 different codes can be generated; more generally, an n-resonator tag of the proposed type can create 6n different codes.