Wireless interrogation of passive antenna sensors

Abstract

Recently, we discovered that the resonant frequency of a microstrip patch antenna is sensitive to mechanical strains or crack presence in the ground plane. Based on this principle, antenna sensors have been demonstrated to measure strain and detect crack in metallic structures. This paper presents a wireless method to remotely interrogate a dual-frequency antenna sensor. An interrogation horn antenna was used to irradiate the antenna sensor with a linear chirp microwave signal. By implementing a light-activated switch at the sensor node and performing signal processing of the backscattered signals, the resonant frequencies of the antenna sensor along both polarizations can be measured remotely. Since the antenna sensor does not need a local power source and can be interrogated wirelessly, electric wiring can be eliminated. The sensor implementation, the signal processing and the experimental setup that validate the remote interrogation of the antenna sensor are presented. A power budget model has also been established to estimate the maximum interrogation range.

Antenna Sensors in Passive Wireless Sensing Systems

“…Even though the backscattered signal power was introduced by Bhattacharyya et al (2009) and Marrocco et al (2009) as an additional sensing parameter for the RFID-enabled antenna sensors, it can only offer a relative measurement and thus share the same limitation as the turn-on power. Wireless measurement of the antenna resonant frequency outside of an anechoic chamber was demonstrated by Tata et al (2009) and Deshmukh and Huang (2010). Using delayed timedomain reflectometry (TDR) and normalized TDR, they validated the linear relationship between the antenna resonant frequency shifts and the applied strain levels experimentally.…”

Patch antenna sensor rosettes for surface strain measurement

“…First, by using cabled measurement, the linear relationship between resonance frequency of the antenna and strain is validated (Tata et al, 2009). The relationship is later verified by wireless interrogation (Deshmukh and Huang, 2010). As the rectangular microstrip patch antenna is sensitive to strain only along the longitudinal direction or the transverse direction, Daliri et al (2012) proposed a circular microstrip patch antenna sensor that responds to surface strain.…”

Sensitivity Modeling of an RFID-Based Strain-Sensing Antenna With Dielectric Constant Change

“…Other researchers have proposed passive wireless strain sensing through analog mechanisms to reduce the complexity of the wireless nodes [10][11][12][13][14]. This passive approach removes the process of onboard digitization, eliminates the requirement for a microcontroller in the sensor node, and usually entails an electromagnetic antenna with known resonance frequency.…”