研究目的
Determination of the complex permittivity and permeability of low-loss materials, eliminating half-wavelength resonances occurring in transmission/re?ection (T/R) measurements.
研究成果
The present approach successfully yields sufficiently flat permittivity and permeability of low-loss materials around the λ/2 resonance, eliminating resonant artifacts and providing very good interpolation that smoothly connects outside-resonance results from the conventional T/R method.
研究不足
The rigorous evaluation of analytical uncertainties in the smoothed permittivity and permeability is not straightforward. The method's accuracy depends on the selection of frequency ranges for smoothing and the window functions applied.
1：Experimental Design and Method Selection:
The approach involves applying time-domain smoothing to remove resonant artifacts from the wave impedance obtained with the conventional T/R method.
2：Sample Selection and Data Sources:
Measurements were conducted on two test materials, nylon and lithium ferrite, using an APC-7 coaxial transmission line.
3：List of Experimental Equipment and Materials:
An HP 8510C VNA was used for S-parameter measurements.
4：Experimental Procedures and Operational Workflow:
The method starts with an assumption that the T/R method ensures a smooth refractive index at all frequencies, employs the inverse discrete Fourier transform (DFT) of a frequency response for the wave impedance, applies windowing to permit zero-time components of the wave impedance, and then applies the forward DFT to this modi?ed time-domain wave impedance.
5：Data Analysis Methods:
The permittivity and permeability are calculated from the smoothed wave impedance and the conventional refractive index.
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