Triangular loop resonator based compact chipless RFID tag

TLDR

The authors introduce a fully passive, chipless RFID tag that encodes 10 bits across 4–11 GHz using a frequency‑selective surface design. The tag consists of a 27.5 × 30 mm² FR4 substrate patterned with triangular loop resonators, where adding or removing nested loops alters the geometry to produce distinct frequency signatures for each bit sequence. The resulting tag is compact, robust, and maintains a stable response to signals incident from varying angles.

Abstract

A novel, frequency selective surface (FSS) inspired, fully passive, chipless data encoding circuit capable of being operated as a radio frequency identification (RFID) tag is presented. The tag is composed of finite repetitions of the unit cell realized on a grounded FR4 substrate having an overall size of 27.5 × 30 mm2. The unit cell is made up of several triangle-shaped resonators patterned in a looped fashion. Variation in the geometric structure of the tag, achieved by addition or removal of nested loops, corresponds to a specific bit sequence. Each sequence is represented in the spectral domain as a unique frequency signature of the resonators. The proposed 10-bit tag covers the spectral range from 4 to 11 GHz. The tag is compact, robust, and exhibits a stable response to impinging signals at different angles of incidence.