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Description
This technique allows a broad band measurement of the complex permeability of isotropic thin layers. The samples under test are placed onto a dielectric holder.
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Principle
This technique is based on the measurement of the impedance of a 2-plate line shunted at one end. The sample consists in a thin or thick, rectangle- or square-shaped layer placed under the line strip in front of the shunt.
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Analysis of measured data
The shunted line constitutes an inductive loop. The complex permeability of the layer, µ*, is determined from the measurement of the inductive loop impedance. To discard the systematic errors inherent in the test devices, e.g. analyzer, line, connector.., a vector subtraction is made between the measurement and the one under load.
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Résultats
- Frequency range used: 130 MHz - 8 GHz (network analyzers HP8720A).
- Type of material tested: isotropic magnetic thin or thick layers.
- Network analyzer calibration: SOLT.
- Dimensions of the tested samples:
- length: 9 mm,
- width: 9 mm,
- thickness: less than 1.8 mm including the substrate that holds the film.
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Permeability spectrum of a 154-mm-thick CoNbZr thin layer onto a rigid substrate
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Comments
The above figure displays the spectrum of a marked gyromagnetic resonance.
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1. J.C. Peuzin, J.G. Gay "Etalons de susceptibilité externe pour la calibration des mesures de perméabilité en radiofréquences ou micro-ondes", JCMN Brest (1994).
2. D. Pain, M. Ledieu, O. Acher, A.L. Adenot and F. Duverger "An improved permeameter for thin film measurements up tu 6 Ghz, 43 rd Annual Conference on Magnetism and Materials Miami, USA (1998).
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