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

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.