Hybrid coding chipless tag based on impedance loading

Hybrid encoding technique is an efficient method to expand the coding capacity in radio‐frequency identification chipless tag design. In this study, a novel hybrid coding technique by combining amplitude deviation and frequency position encoding is proposed. The proposed tag is based on three circle ring resonators with loaded resistors. A transmission line model is employed to illustrate the operation principle of the impedance loading technique. A coding capacity of at least 23.7 bits is obtained within a compacted dimension of 3 cm × 3 cm. Corresponding experiments on realised prototypes are provided to validate the effectiveness of the proposed design.