研究目的
To investigate the effect of magnetic permeability on permittivity measurement using a coaxial line reflection technique and to develop an improved method for accurate complex permittivity measurement of ferrite materials over a wide frequency range.
研究成果
The slotted coaxial sample technique effectively reduces the impact of magnetic permeability on permittivity measurements, providing accurate results for ferrite materials. It is validated through simulations and experiments, showing close agreement with reported data. Recommendations include using slotted samples and optimizing sample length for future applications.
研究不足
The technique requires cutting an air slot in the sample, making it partially destructive. Sample length must be small compared to wavelength, limiting applicability for high-permittivity materials. There may be remnant errors due to magnetic permeability effects not fully eliminated.
1：Experimental Design and Method Selection:
The methodology involves designing a coaxial reflection technique with a slotted coaxial sample to minimize the effect of magnetic permeability. Theoretical models include impedance analysis using transmission line theory and electromagnetic simulations with CST Microwave Studio.
2：Sample Selection and Data Sources:
Samples include Teflon (non-magnetic) and NiZn ferrite (magnetic) materials, with dimensions compatible with APC-07 standards (3.05 mm inner diameter, 6.95 mm outer diameter, 2-2.5 mm length). Data is acquired using a vector network analyzer.
3：05 mm inner diameter, 95 mm outer diameter, 2-5 mm length). Data is acquired using a vector network analyzer.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment includes a vector network analyzer (Keysight N9915A), coaxial fixture, slotted and non-slotted cylindrical samples, and a diamond wheel cutting machine (Metatech Metacut - HSDCM). Materials are ferrite and dielectric samples.
4：Experimental Procedures and Operational Workflow:
The fixture is directly mounted to the VNA port. S11 scattering parameter is measured over 20 kHz to 1 GHz. Smith chart is used to display impedance. A MATLAB program processes data to calculate complex permittivity.
5：Data Analysis Methods:
Data analysis involves extracting capacitive and resistive components from impedance measurements, using MATLAB for reverse calculation of permittivity, and comparing with simulated results from CST Microwave Studio.
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