Passive wireless antenna sensor for strain, temperature, crack and fatigue measurement

摘要

An apparatus and method is provided for monitoring a condition of a structure using a passive wireless antenna sensor having a known resonant frequency when mounted on the structure. A signal is transmitted with sweeping frequencies around a known resonant frequency to the passive wireless antenna sensor. A signal is received from the passive wireless antenna sensor and a resonant frequency of the passive wireless antenna sensor is determined based on the received signal. The determined resonant frequency is then compared to the known resonant frequency, whereby a change in the resonant frequency indicates a change in the condition of the structure.

主权项

1. A method of monitoring a condition of a structure, comprising:
transmitting, at a first time, an interrogation signal to a passive wireless antenna sensor mounted on the structure, wherein the interrogation signal includes frequencies in a frequency range, wherein the frequency range includes a resonant frequency of the passive wireless antenna sensor, wherein the passive wireless antenna sensor is configured such that a change in the condition of the structure will change the resonant frequency; receiving a first backscattered signal, wherein the first backscattered signal comprises an antenna backscattered signal from the passive wireless antenna sensor and a structure backscattered signal from the structure, wherein the antenna backscattered signal is modulated by the passive wireless antenna sensor at a modulated frequency; detecting a first envelope of the first backscattered signal; normalizing the first envelope; selecting a reference amplitude; determining a first frequency of the first envelope that is associated with the reference amplitude; transmitting, at a second time, the interrogation signal to the passive wireless antenna sensor mounted on the structure; receiving a second backscattered signal, wherein the second backscattered signal comprises an antenna backscattered signal from the passive wireless antenna sensor and a structure backscattered signal from the structure, wherein the antenna backscattered signal is modulated by the passive wireless antenna sensor at a modulated frequency;detecting a second envelope of the second backscattered signal;
normalizing the second envelope; determining a second frequency of the second envelope that is associated with the reference amplitude;determining a frequency shift based on a difference between the first frequency and the second frequency; and
determining the condition of the structure based on the frequency shift.