Strain Detection for Structural Health Monitoring Using Circularly-Polarized Patch Antenna Sensor

In this paper, a new method for strain detection of metallic structures using input admittance variation of circular polarization (CP) antenna sensor is proposed. The CP patch antenna is excited via a proximity-coupled microstrip line. To minimize the antenna sensor's size, RT/duroid
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3010 high frequency laminate is used for the fabrication of antenna sensor, thus a small footprint of 17.6mm×18.4mm can be realized. Bidirectional strain sensing has been implemented by using a proof-of-concept prototype. High sensitivities of 25.2 and 23.9 ppm/με have been achieved for tensile and compression strain, respectively.