Influence of mutual coupling on performance of small scatterers for chipless RFID tags

The paper introduces the two new size-reduced planar scatterers for chipless RFID and explores the influence of mutual coupling of two-element array on their performance. Radar cross section (RCS), and resonant frequency has been evaluated by EM simulation and from S-parameters measured when scatterers have been placed in parallel-plate waveguide. The results clearly show the trade-off between size reduction and RCS proportional to read range of the proposed configurations. Closely spaced resonators are strongly coupled which negatively affects uniformity of their RCS response. Simple geometrical modification of scatterer layout that reduces such unwanted effect is proposed. This results in the development of new smaller uniplanar chipless tags with higher information density.