Electromagnetic optimization of passive RFID sensor nodes

RFID passive tags are nowadays starting to be considered more than labeling devices: by properly analyzing the two-ways communication link it is possible to get information about the state of a tagged object, without any specific embedded sensor or local power supply. Despite of the generality and the straightforwardness of the approach, the design of such a class of devices requires specific strategies to make the radio-sensors able to properly track the evolution of the phenomena under observation, jointly optimizing communication and sensing requirements. In this paper the optimization problem is formalized by means of convenient matching charts and evaluated in realistic experimental examples.