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.