Design Guidelines for Gap Coupled Spiral Microstrip Resonators in Chipless RFID Tags

This paper presents a qualitative analysis of the impact of variations in the physical dimensions of gap coupled spiral resonators on the resonating frequency and attenuation level in multi-resonant circuits. For this analysis, the mean absolute deviation of each of the swept parameters was computed to conclude on how much they vary in relation to the mean value. It was concluded that the value of the length of the gap coupled spiral is the parameter that mainly defines the value of the resonating frequency and that the distance between the spiral and the transmission line mainly defines the attenuation level. The validation of the model of our previously published paper is further reinforced, and general guidelines for the design are given. With this work, the design process of gap coupled spiral resonators for chipless RFID tags become much more simple and more manageable.