Environmental Engineering Reference
In-Depth Information
The final TL model and the values of the added lumped (parasitic) elements are
shown in Fig. 4.14. In the implemented model, TL 1 represents the SMA 3.5 mm
adapter; TL 2 represents the probe filled with the LUT; C 1 , L 1 represent the non-
ideal transition adapter/probe; and R 1 , R 2 , L 2 represent the non-ideal short circuit at
the end of the probe. C 1 is proportional to the real part of the dielectric permittivity
of the considered liquid, Real(
ε liquid ).
Fig. 4.14 Transmission line model (as implemented in MWO) of the used measurement cell
[8]
4.4.1.1
Validation of the Method through Measurements on
Well-Referenced Materials
The appropriateness of the TL model in estimating the Cole-Cole parameters of
the LUTs was verified through further measurements on 1,1,1-trichloroethane and
ethyl acetate. In this case, starting from the implemented TL model (now includ-
ing all the evaluated parasitic components), the Cole-Cole parameters of the liquid
were considered as the minimization variables. TDR measurements (along with the
corresponding frequency domain processing and minimization) were repeated ten
times for each considered material (each time, by emptying and refilling the probe).
In this way, it was possible to assess the repeatability of measurements and to
reduce random errors contributions. The four evaluated Cole-Cole parameters are
summarized in Table 4.8 and Table 4.9 (static conductivity is negligible for both liq-
uids): each set of parameters was evaluated as the average of the results of ten min-
imizations over the ten measurements. In order to identify a figure of merit for the
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