Intensity variations of the backscattered power from an RFID tag have been demonstrated to be a potential wireless solution to measure material deformation. This paper discusses the design and performance of a flexible tag antenna equipped with novel inductively-coupled RFID microchip for use as a wireless strain sensor. Dielectric characterization of a flexible substrate has been carried out to properly design and simulate the proposed antenna design. Due to the balanced nature of this radiating element, differential scattering parameter measurements were performed to characterize the antenna input impedance. Finally, measurements of the backscattered power as a function of radial deformations are also shown as a qualitative analysis of the strain sensing capabilities.