A Compact and Low-Cost Hybrid Reader for Chipless RFID Systems

Chipless radio frequency identification (RFID) offers a cost-effective and sustainable alternative to conventional RFID by eliminating integrated circuits in tags. In this work, we introduce a hybrid reader architecture for frequency-coded chipless RFID tags, combining the strengths of both time-domain and frequency-domain readers. The proposed system features a Gaussian impulse-based interrogation transmitter, realized using either a commercial impulse generator or a novel, low-cost logic gate-based impulse generator, and a software-defined radio (SDR) for wideband spectral analysis during reception. This design is compact, self-contained, and low-cost, making it well-suited for large-scale deployments. Experimental evaluations demonstrate reliable resonance detection and tag identification, with results closely matching those from a vector network analyzer (VNA). The reader achieves 1 MHz–6 GHz coverage and completes full-spectrum measurements in under 800 ms, showing less than 1.09% frequency deviation compared to the VNA. Furthermore, using the proposed reader, a machine learning-assisted tag identification experiment was conducted, yielding robust tag classification under noisy conditions, with accuracies of up to 98%.