Automated Design and Miniaturization of RF Resonators Based on the Cesàro Fractal for Chipless RFID Tags
Keywords:
Chipless RFID, Fractal resonator, Cesàro fractal, miniaturization, electromagnetic simulation, HFSS, PythonAbstract
This paper presents an automated methodology for the design and miniaturization of novel resonators based on the modified Cesàro fractal. The resonators are generated using Python scripts integrated with the HFSS electromagnetic simulator and offer a compact alternative to conventional square-loop resonators for chipless RFID tags. A key advantage of the proposed approach is the ability to iteratively miniaturize the structures, resulting in a significantly reduced tag footprint. The Cesàro fractal, an adaptable derivative of the Von Koch curve, is explored here by treating the traditionally fixed 60° deformation angle as an adjustable parameter. This flexibility enables precise geometric optimization of the resonator for operation at target frequencies. The methodology encompasses theoretical analysis of fractal parameters such as the angle and fractal order. The script-based geometry generation, full-wave electromagnetic simulation, device fabrication, and experimental validation through comparison of simulated and measured results. The use of the Cesàro fractal is justified not only by its inherent miniaturization capability but also by the finer control it provides over the resonant frequency. We demonstrate that varying the structure’s perimeter allows for precise tuning of the resonant frequency without incurring an undesirable increase in resonator area. When a resonator is detuned, no energy coupling occurs, resulting in a high signal level at the output port, corresponding to a logical “1” state, which is essential for chipless RFID encoding. Experimental results confirm the efficiency of the Cesàro fractal as a viable alternative to conventional square-loop resonators, highlighting its potential for compact, high-performance RFID systems.
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