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Description
This single-frequency resonant measurement method enables one to characterize solid and isotropic dielectric materials in the form of rectangular plates or thick layers.
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Principle
The sample to be characterized is directly put onto a transmission line shunted with respect to the main line made in microstriigure). Sij, the distribution parameters of the measuring device are measured with a vector network analyzer associated to a universal test bench. (Picture). In addition to avoiding problems in relation with sample machining, the main asset of this method stands in the quite simple electromagnetic analyp technology (Top Fsis associated to the cell that enables one to get the dielectric properties of the tested material from Sij-parameters.
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Analysis of measured data
The analysis of Sij parameters of the device under test allows the measurement of the resonant frequency along with the calculation of the quality factor under load, i.e. when the dielectric sample is present. The knowledge of this resonant frequency leads to the real part e'eff of the complex effective permittivity of the resonant structure: eeff=e'eff -je"eff. Once the quality factor has been determined, one can get the imaginary part, e"eff. Then, further to the calculation of e'eff and e"eff, an optimization procedure gives e'eff et e"eff of the dielectric material to be characterized.
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Results
- Operating frequencies: close to 3GHz, 8.82GHz and 14.35 GHz (network analyzer HP8510B and Wiltron measurement cell on the wafer.
- Type of material tested: dielectric with losses from mean to high, (tand >10-3).
- Accuracy: relative error < 6%.
- Network analyzer calibration: TRL.
- Dimensions of the tested samples: maximum length: 10 mm; width: a few mm; thickness: from a few tens of µm to few mm
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Décalage de la fréquence de résonance du stub dû à l'introduction de l'échantillon
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Comments
To validate this method experimental permittivity values of several dielectric materials have been calculated from the measured S12 distribution parameter (figure) and then compared to those reported in the literature.
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