Long-Range Displacement Meters Based on Chipped Circular Patch Antenna

Abstract

This paper presents a passive wireless long-range displacement sensor that is based on the circular patch antenna, and the detecting range of the sensor can be customized. The sensor consists of a chipped circular antenna with two opened rectangular windows, a substrate, and a ground plate with a sloping channel. No bonding between the antenna and the ground plate allows for the chipped antenna to slide along the sloping channel. The channel will drive the current flow on the plate once the chip is activated, increasing the effective electrical length and, consequently, decreasing the resonant frequency of the circular antenna. The sensing mechanism equates the measuring displacement to the relative movement of the antenna with respect to the ground that achieves the measurement of long-range displacement and, thus, the proposed sensor can avoid stress damage to the antenna due to excessive deformation. Three different range sensors were simulated in the the Ansoft high frequency structure simulator (HFSS). The results show that the resonance frequency of the antenna has a linear relationship with the varying chute depth beneath the chip. Three sensors were fabricated, and the experimental results also validated that the sensitivity of the sensor can be adjusted.

Fabrication and Investigation of Deformable Rubber–Carbon Nanotube–Glue Gel-Based Impedimetric and Capacitive Tactile Sensors for Pressure and Displacement Measurements

“…The optical displacement of the sensor's properties was also described by Jakson et al [29]. Xue et al [30] patented a long-range displacement passive wireless sensor that consisted of a substrate, a sloping channel ground plate, and a chipped circular patch antenna with two opened windows of rectangular shape. The lack of bonding between the ground plate and antenna allowed the antenna (chipped) to slide along the slopping channel.…”

A Capacitively-Fed Inverted-F Antenna for Displacement Detection in Structural Health Monitoring

“…The helical antenna [27] is for built-in application; the patch antenna fed by capacitive microstrip lines [33] and the patch antenna with overlapping sub-patch [34] have great sensitivity with small measuring range, which is suitable for crack propagation monitoring; the sensor with complementary split-ring resonators [44] can measure two-dimensional displacement; and the inverted-F antenna-based sensor [45] is designed for the measurement of displacement on metal surfaces. Compared with the sensor in [23], the CFIFA-based sensor has higher sensitivity, and by adjusting the dimensions of the CFIFA, the CFIFA-based sensor can obtain a larger measuring range. Compared with the sensor in [43], the CFIFA-based sensor has a greater measuring range and a similar sensitivity.…”

An off-center fed patch antenna with overlapping sub-patch for simultaneous crack and temperature sensing

“…In addition, the antenna's electromagnetic waves can penetrate non-metal coverings, making antenna-based sensing technology better suited for structural health monitoring. Various antenna-based sensors have been proposed for many tasks, including strain sensing [18][19][20], crack sensing [21], displacement sensing [22][23][24], temperature sensing [25], humidity sensing [26], bolt loosening detection [27], and cement hydration setting time detection [28]. Some early antenna-based sensors only tracked the change of a single physical variable.…”