Comparative study on directional sensitivity of patch‐antenna‐based strain sensors

Abstract

In this article, we present a comparative study into the directional sensitivity of patch-antenna-based strain sensors. Two linearly-polarized (LP) patch sensors vs a circularly-polarized (CP) patch sensor with identical configurations are demonstrated. The strain occurred in real structures is commonly uncertain, the usefulness of LP-patch sensor becomes limited. Like the conventional strain gauges, it can only be used if the strain direction is known beforehand. Therefore, a nearly-square CP-patch sensor for multi-directional strain monitoring is proposed here. In order to obtain high sensitivity, three novel strain sensing methods are proposed for strain monitoring. Multi-directional strain sensing is achieved by a proof-of-concept prototype. The simulated results verified by experimental results show that high sensitivities of these three methods were achieved.

A Highly Sensitive Microwave Patch Sensor for Multidirectional Strain Sensing Based on Near Orthogonal Modes

“…Strain sensing parameters of LP patch can only be based on single mode's resonant frequency shifts, whereas the CP-patch generates simultaneously two radiation modes. This CP-patch sensor exhibits at least 55 times more sensitive than the LP-patch counterpart by the proof-of-concept prototype [33]. In this paper, we further extended our studies from the probe-feed to microstrip-line feed patch sensor, where the microstrip-line is integrated with the strain sensor as a whole so that artificial hole is not required to accommodate the coaxial feed on the metallic structures in order to fulfill the integrity of structure.…”

“…A sensor of single-feed circularly polarized (SFCP) patch based on orthogonal mode was first initiated by the authors [33], where we presented a comparative study into the directional sensitivity factor of two coaxial probe-fed LPpatch sensors and CP patch. The physical configurations between CP-and LP-patch were maintained to be the same except the feed positions.…”

Application of a Single Cell Electric-SRR Metamaterial for Strain Evaluation

“…Microstrip antennas for strain measurements have been proposed and developed in recent years [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. The vector network analyzer (VNA) measures the frequency domain reflection coefficient ( S 11 ) of the microstrip antenna sensor.…”

“…In this type of sensor, the reflection coefficient as a function of frequency is monitored to determine the deformation based on the resonant frequency shifts. The sensors were fed in wired form [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 16 , 17 , 18 , 19 , 20 , 22 , 24 , 25 ] and wireless [ 15 , 21 , 23 ]. The first and most studied sensor geometry is the rectangular microstrip strain sensor [ 8 , 9 , 10 , 11 , 12 , 18 , 19 , 20 , 21 , 24 ].…”

“…The sensors were fed in wired form [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 16 , 17 , 18 , 19 , 20 , 22 , 24 , 25 ] and wireless [ 15 , 21 , 23 ]. The first and most studied sensor geometry is the rectangular microstrip strain sensor [ 8 , 9 , 10 , 11 , 12 , 18 , 19 , 20 , 21 , 24 ]. This geometry provides the highest sensitivity at a given resonance frequency.…”