Broadband permeability measurement of ferromagnetic thin films or microwires by a coaxial line perturbation method

Abstract

A new method to measure the microwave permeability of ferromagnetic thin film or microwires from 50 MHz up to 18 GHz is presented. In contrast with all previous permeameters based on perturbation techniques, our permeameter does not require any reference sample for calibration, which is a definite advantage, as it is very difficult to have a reference magnetic sample of known permeability. In our technique, a network analyzer detects the small perturbation of the impedance of a coaxial line cell loaded by the magnetic sample. Satisfactory sensitivity is achieved, even for magnetic volume fraction as low as 10−4. To assess the validity of this new technique, comparisons are performed with three other methods on different samples, in particular on ferromagnetic wires. It is shown that in the case of very soft magnetic materials, the shape of the sample affects the permeability measured with a conventional permeameter.

Microwave properties of ferromagnetic composites and metamaterials

“…Corrected measurements for the reduction of the sample size are detailed in Ref. [17] The samples are composed of periodically spaced metamaterial blocks so that the sample complies with the symmetry and the field configuration of the measurement setup (details in Fig. 7).…”

Measure the Complex Permeability of Ferromagnetic Thin Films: Comparison Shorted Microstrip Method With Microstrip Transmission Method

“…However, this technique is ill suited for conductive materials, particularly when the sample under study is a low-resistive film [1]. For metal films deposited on a flexible polymer substrate, coaxial line perturbation method has good performance [2]. Whereas for the magnetic thin films deposited on rigid substrate, the planar transmission-line (i.e., microstrip [3][4][5]) methods are more suitable.…”

Technique under compressive stress for determining the magneto-elastic effects in ferrites

“…In that case, standard measurement procedure (R/T, TEM calculations) gives the effective properties of the medium between the alumina layers (air+ferrite). Using static-like calculations, the intrinsic properties of the material samples are deduced [4].…”