Passive Environmental Sensing

Various sensors, systems, and methods for monitoring environmental conditions are provided. In one embodiment, among others, a passive sensor includes an antenna; a modulating circuit coupled to the antenna by a microstrip transmission line, the modulating circuit capable of modulating a backscattered signal; a sensing material disposed between the microstrip transmission line and a ground plane of the passive sensor, where an electrical property of at least a portion of the sensing material varies with the environmental condition; and where the modulated backscattered signal includes at least one of phase and amplitude information corresponding to the electrical property of the portion of the sensing material.Georgia Tech Research Corporatio