## 3 Results and Discussions
\begin{table}
\begin{tabular}{c c c} \hline
**FOM** & **Indicator** & **Suitable Frequency (GHz)** \\ \hline \multirow{2}{*}{FOM1} & Real part of complex relative & \\  & permittivity (\(\epsilon^{\prime}_{r}\)) & 0.60 \\ \hline \multirow{2}{*}{FOM2} & Electrical conductivity (\(\sigma\)) & 3.74 \\ \hline \multirow{2}{*}{FOM3} & Phase constant (\(\beta\)) & 4.00 \\ \hline \end{tabular}
\end{table} 
Table 2: Comparison of FOMs in experiments of honey samples. Figure 11: The FOM1 is depicted from the frequency range of 0.5-4.0 GHz. Figure 12: The FOM2 is depicted from the frequency range of 0.5-4.0 GHz. relative permittivity at the frequency of 0.6 GHz has the polynomial relationship with the adulterations. The relationship is shown in Equation (13) and Figure 14 shows the curve fitting of real part of relative permittivity at 0.6 GHz on water adulteration in honey samples with R\({}^{2}\) of 0.9968. \[\epsilon_{r}^{\prime}=p1*x^{2}+p2*x+p3, \tag{13}\]  
where \(p1=-0.006279\), \(p2=1.268\), \(p3=20.05\) and x = %\(w/w\) at 0.6 GHz. It is found in the regression analysis for electrical conductivity that the electrical conductivity at the frequency of 3.74 GHz has the polynomial relationship with the adulterations. Equation (14) shows the relationship and Figure 15 shows the curve fitting of electrical conductivity at 3.74 GHz on water adulteration in honey samples with R\({}^{2}\) of 0.9833. \[\sigma=p1*x^{2}+p2*x+p3, \tag{14}\]  
where \(p1=-0.0007925\), \(p2=0.08857\), \(p3=1.212\) and x = %\(w/w\) at 3.74 GHz. Figure 14: The curve fitting of the real part of complex relative permittivity at the frequency of 0.6 GHz. Figure 13: The FOM3 is depicted from the frequency range of 0.5–4.0 GHz. In the regression analysis for phase constant, it is found that the phase constant at the frequency of 4.0 GHz has the polynomial relationship with the adulterations. Equation (15) shows the equation and Figure 16 shows the regression of phase constant at 4.0 GHz on water adulteration in honey samples with R\({}^{2}\) of 0.9977. \[\beta=p1*x^{2}+p2*x+p3, \tag{15}\]  
where \(p1=6.634\times 10^{-6}\), \(p2=0.006855\), \(p3=0.2673\) and x = \(\%w/w\) at 4.0 GHz. From the curve fittings, it is shown that the real part of complex relative permittivity, the electrical conductivity, and the phase constant models given in Equations (13)-(15) could accurately describe the real part of permittivity (0.6 GHz), the electrical conductivity (3.74 GHz), and the phase constant (4.0 GHz) with the water adulteration in honey samples, respectively. The proposed technique is successful in determination of the complex relative permittivity of the honey samples. Further study is performed on the natural latex samples to obtain the initial results. The experimental setup is shown in Figure 5. After the mea  
Figure 16: The curve fitting of the phase constant at the frequency of 4.0 GHz. Figure 11:0 The curve fitting of the electrical conductivity at the frequency of 3.74 GHz. surement is performed, the dry rubber content (DRC) of the natural latex is determined as shown in Figure 11:1 The obtained DRC is 35.27%\(w/w\). In Figure 18, the proposed technique can be used to determine the complex relative permittivity of the natural latex samples. The real part is in the range of 34-37 while the imaginary ranges from 7-14. From the results in Figure 18, it is possible to apply the proposed sensor to determine the DRC in different concentrations and choose the suitable frequency for the determination of the DRC. Figure 11:2 The determination of DRC in the natural latex samples. Figure 11:3 The complex relative permittivity of natural latex over the frequency range of 0.5–4.0 GHz at the temperature of 25 \({}^{\circ}\)C.  
Generally, DRC is inversely proportional to the water content of the natural latex sample.