Microwave stress monitoring using Co-rich amorphous microwire assessed by free space measurements

We provide new experimental results on studies of the effect of applied stress on Reflection coefficient (S₂₂ parameter) of Co-rich glass-coated ferromagnetic microwire measured using free space microwave spectroscopy. Studied Co-rich microwire with vanishing magnetostriction coefficient presents high Giant magnetoimpedance (GMI) effect associated with excellent soft magnetic properties. Tensile stress was applied through the mechanical load, attached to the single Co-rich microwire sample inside the anechoic chamber and the S₂₂ parameter was measured at 2.45 GHz using broadband horn antennas and a vector network analyzer. Upon tensile stress (up to 225 MPa), we observed a substantial change in the S₂₂ parameter. The change in the S₂₂ parameter correlates with the stress dependence of hysteresis loops. The experimentally discovered stress dependence of the reflection coefficient allows for contactless stresses and damage monitoring of composites with microwire inclusions.