Application of antenna in strain measurement

A multi-band antenna which can be used as a passive strain measurement device is presented. The dimensions of the antenna will change when different strains are applied, resulting in changes in the resonant frequencies. The proposed antenna resonates at multiple frequencies. By creating slots on the patch of the antenna, these resonant frequencies shift to a higher or a lower value for different strain orientation along the length or width. By measuring the resonant frequencies of the antenna, the corresponding strain applied to the antenna is identified, leading to the strain measurement. To verify our design concept, a prototype antenna was fabricated using Rogers RT/duroid substrate with a thickness of 0.254 mm. The total length and width of the antenna is 19.8 mm and 17.9 mm, respectively. The simulated and measured results along with the mechanical testing procedure have been presented, which are consistent with each other.