Utilising microstrip patch antenna strain sensors for structural health monitoring

In this article, the feasibility of using a circular microstrip patch antenna to measure strain and the effects of different materials on sensitivity of the patch antenna are investigated. Also, the effect of strain direction on the frequency shift is studied. The theoretical model shows a linear relationship between strain and the shift in the resonant frequency of the antenna in any material. Both finite element analysis (FEA) and experimental tests have been undertaken to corroborate the relationship between strain and frequency shift. In addition, a new antenna sensor based on a meandered microstrip patch antennas has been designed and tested to overcome the shortcomings of the circular patch. The meandered circular microstrip patch antenna exhibited a threefold increase in sensitivity and a fivefold reduction in its physical size, when compared to the simple circular patch. The ultimate intention of this work is to configure antennas for the detection of relatively small damage zones in structures and to do so wirelessly.