Assessing the Impact of Data Filtering Techniques on Material Characterization at Millimeter-Wave Frequencies

Abstract

This paper reports on an investigation into data filtering techniques for material characterization using a commercially available WR-15 (50-75 GHz) material characterization kit (MCK). The MCK uses a guided free-space method (operating like the conventional quasi-optical focused beam system) that enables measurement of S-parameters of dielectrics using a vector network analyzer (VNA). Multiple reflections and resonances exist in the MCK and they cannot be readily eliminated by calibration. To minimize these effects on extracting dielectric constant and loss tangent from the measured S-parameters, data filtering techniques (e.g. Savitzky-Golay filter and time-gating) can be adopted. A comparison of measurement results using these two techniques was carried out on five common dielectric materials. Generally, the results obtained using these two filtering techniques are consistent with each other, and the Savitzky-Golay filter offers better performance in the scenario where the specimen quality is not ideal. Three specimens were also measured using an open-resonator (operating at 36 GHz). There is generally good agreement between results from the MCK and the open-resonator.

Ultra‐Wideband Integrated Graphene‐Based Absorbers for Terahertz Waveguide Systems

“…These effects inhibited the accurate measurement of the sample material. Time gating could be used to correct such effects [ 50 ] and was applied to all measured data. A time gate of length 0.8–1 ns was first applied to the measurement of the empty reference waveguides, wherein the correct location for the gate was determined from the time domain response of the empty waveguide.…”

Reference-Plane Invariant Free Space Dielectric Material Characterization up to 330 GHz

“…In this sense, several techniques for smoothing the results to make them more reliable can be found in the literature. One of the most outstanding techniques is the one proposed in [15], using Savitzky-Golay filters. In this case, it has been demonstrated that using these filters is equivalent to, or even more efficient than, using other techniques, such as time-gating, when it comes to reducing possible signal interferences, such as reflections in the measurement system.…”