Comparison between Cross-polarization and Circular Polarization Interrogation for Robust Chipless RFID Reading

Circular polarization for chipless tag interrogation has recently been presented as an improvement over the conventional cross-polarization method as it is supposed to be both orientation-independent and able to isolate the tag from its environment. In this article, we make a systematic comparison between the two approaches. We show, from both theory and measurements, that for the circular polarization approach, the assumptions of orientation independence and isolation are valid only for very specific and non-realistic environments. A new tag has been used for the characterization. It can be manufactured by hand in less than five minutes at negligible cost and yet has performances comparable to optimized tags, making it ideal for rapid prototyping.