Wireless ferroelectric resonating sensor.

This paper presents a passive wireless resonating sensor that is based on a ferroelectric varactor. The sensor replies with its data at an intermodulation frequency when a reader device illuminates it at 2 closely located frequencies. The paper derives a theoretical equation for the response of such a sensor, verifies the theory by simulations, and demonstrates a temperature sensor based on a ferroelectric varactor.

Estimator for reflective delay line-type SAW sensors.

This correspondence presents an estimator for reflective delay line-type surface acoustic wave (SAW) sensors. The estimator is derived from an analytical model and its range of validity is discussed. The proposed estimator enables simultaneous access to several SAW sensors with time-orthogonal responses and it can be implemented in a computationally efficient way utilizing the fast Fourier transform algorithm. The estimator is experimentally verified and its performance is compared with that of a reference estimator.

Optimized signal processing for FMCW interrogated reflective delay line-type SAW sensors.

This correspondence presents an optimized frequency modulated continuous-wave (FMCW) interrogation procedure for reflective delay line-type SAW sensors. In this method, the time delays between reflections are obtained with Fourier transform from optimally windowed frequency response. Optimal window functions maximize the signal-tointerference ratio at chosen temporal points of interest. The method is experimentally verified and its accuracy is compared with that of a Fourier transform from Hamming-windowed frequency response.