Theoretical Intrinsic Equivalent Magnetic Noise Evaluation for Magneto (Elasto) Electric Sensors Using Modulation Techniques

The equivalent magnetic noise of magnetostrictive-piezoelectric composite sensors, in the passive mode or when magnetic modulation techniques are used, has been investigated theoretically and compared with measurements. Several main noise sources and their contributions to the equivalent magnetic noise spectral density have been analyzed using the fluctuation-dissipation theorem and modeled via Nyquist´s noise-expression in the linear and non-linear regime. These theoretical analyzes show that the mechanical loss, related to the interfriction of composites, appears as the dominant noise source for such magnetoelectric modulation techniques.