Multi-Bit Chipless RFID Sensing Methodology for Rotation Determination.

Chipless RFID tags can be used for both identification and sensing applications. While binary codes are assigned to the responses of ID tags, they typically are not assigned to the responses of sensing tags. Instead, changes in tag response characteristics, like notches, are related to a sensing parameter. While this provides for a straightforward sensing mechanism, it can be limiting in terms of the dynamic range and sensing resolution that can be achieved. This paper proposes assigning multi-bit codes to the responses of sensing tags in order to better capture the effect of the sensing parameter on the tag response and provide greater sensing capabilities. This is done in the context of a rotation sensing with a tag that is capable of sensing 1° rotations from 0° to 180°. It is also shown that using tags with higher notch densities for sensing can result in better sensing resolution.