A chipless HF RFID tag with signature as a voltage sensor

A working RFID tag used as a The proposed tag has the ability Fig.4 The readings of two tags. Conclusion D C voltage sensor with a spectral signature circuit was produced. to operate in a wireless sensor network since it can be identified by a unique signature. The sensor exhibits a linear range that depends upon the varactor used in the design and allows one to limit the use of bandwidth by using the same frequency band for the voltage sensing and adding only one particular resonant frequency to distinguish which tag is being read. Also, the fact that the produced circuit uses only passive components, the cost to produce such tags is kept very low.