Effects of Electrical Contact on Unstressed Patch Antenna Sensors

To avoid the bearing stress on the monolithic patch antenna sensor for material deformation sensing, the unstressed patch antenna sensor using multiple patch components has been proposed for easy deployment. A typical unstressed sensor utilizes the relative position between a shorted subpatch and a radiation patch as the deformation-sensing unit. However, the electrical contact condition between two patches and copper rusting will affect the performance and reliability of the unstressed sensor during practical application. In this article, the authors alleviate this effect by applying conductive grease between the shorted subpatch and the radiation patch. The equivalent circuit of an unstressed sensor with a shorted subpatch is established first. The different electrical contact conditions are regarded as different capacitors and resistances in this model. Both simulations and experiments are conducted to investigate the effect of different contact conditions on the sensitivity of the sensor. Furthermore, the authors conducted experiments on patch antenna sensor with a copper-coated surface that had experienced rusting. The finding reveals that applying copper-containing conductive grease between the shorted subpatch and the radiation patch enhances sensitivity and reliability of the sensor, resulting in an improvement of up to 32%.