Embodiments of the present invention provide a passive radio frequency identification (RFID) moisture sensor. This moisture sensor includes one or more antenna structures having a tail. The tail is operable to transport a disturbance such as, but not limited to fluid or moisture from a monitored location wherein the antenna has an impedance and varies with proximity to the disturbance. An integrated circuit couples to the antenna structure. This IC includes a power harvesting module operable to energize the integrated circuit, an impedance-matching engine coupled to the antenna, a memory module, and a wireless communication module. The impedance-matching engine may vary a reactive component to reduce a mismatch between the antenna impedance and the IC and produce an impedance value (sensor code) representative of the reactive component impedance. The memory module stores the impedance value (sensor code) until the wireless communication module communicates with an RFID reader and sends the impedance value/sensor code to the RFID reader. The RFID reader may then determine an environmental condition such as the presence of moisture or fluids at the tail of the RFID sensor. This sensor may deploy several antenna and/or tails sensitive to unique disturbances. These tails may be used to monitor different locations as well as different types of fluids. In one particular embodiment, the disturbance is a fluid or moisture within the gutter of a vehicle body.
