## 3 Results
### Dependence of the Convective-Microwave Zone's \(Q\)-Factor on the Moisture Content in Grain  
These studies were carried out in two steps. In the first stage, the influence of the waveguides introduced into the convective-microwave zone on the \(Q\)-factor value was evaluated. In the second stage, the change in the convective-microwave zone's \(Q\)-factor was studied for grain of various moisture contents in the presence of waveguides. Simulations were performed to determine the \(Q\)-factor using the software package CST Microwave Studio 2019 in order to ascertain how and to what extent waveguides in the microwave active zone affect the \(Q\)-factor. Two configurations of the microwave-active zone casing were studied, i.e., with (Figure 9b) and without waveguides (Figure 9a). Results of calculations are presented in Table 1.  
It is evident from the data presented in Table 1 that, for the microwave-active zone without waveguides (in italics), the third and fourth frequency modes are the most closely adjacent frequencies to that of the magnetron (2.45 GHz). However, their corresponding \begin{table}
\begin{tabular}{c c c c} \hline \hline
**No.** & **Resonance Frequency (GHz)** & \(Q\)**-Factor** & **Accuracy** \\ \hline \multicolumn{4}{c}{Microwave-active zone without waveguides} \\ \hline \hline
1. & 2.40107 & 8.321 & 4.862 \(\times\) 10\({}^{-4}\) \\ \hline
2. & 2.409471 & 32.5 & 6.308 \(\times\) 10\({}^{-4}\) \\ \hline
3. & 2.445958 & 2.624 & 4.601 \(\times\) 10\({}^{-4}\) \\ \hline
4. & 2.45099 & 1.939 & 1.705 \(\times\) 10\({}^{-4}\) \\ \hline
5. & 2.455016 & 1.212 & 4.393 \(\times\) 10\({}^{-4}\) \\ \hline \multicolumn{4}{c}{Microwave-active zone with waveguides} \\ \hline \hline
1. & 2.456675 & 15.93 & 2.321 \(\times\) 10\({}^{-8}\) \\ \hline
2. & 2.461078 & 11.78 & 2.418 \(\times\) 10\({}^{-8}\) \\ \hline
3. & 2.469784 & 3.044 & 4.793 \(\times\) 10\({}^{-8}\) \\ \hline
4. & 2.470463 & 21.66 & 2.008 \(\times\) 10\({}^{-8}\) \\ \hline
5. & 2.478836 & 2.795 & 1.844 \(\times\) 10\({}^{-8}\) \\ \hline \end{tabular}
\end{table} 
Table 1: Modes of resonance frequencies and \(Q\)-factor, for convective–microwave zone with and without waveguides. Figure 9: Layout of the microwave-active zones used in \(Q\)-factor calculations: (**a**) casing of the microwave-active zone without waveguides; (**b**) casing of the microwave-active zone with waveguides. \(Q\)-factor values are not high (2.624 and 1.939, respectively). The results of calculating the microwave-active zone with four waveguides show that for this microwave-active zone design option, the most closely adjacent resonance frequency equals 2.456675 GHz (in italics). The \(Q\)-factor value for this frequency is 15.93. There is no resonance frequency closely adjacent to that of the magnetron. These simulation results provide evidence that introducing any technological equipment into the so-called resonators leads to a substantial change in the \(Q\)-factor. The dependence of the \(Q\)-factor on the moisture content in the grain loaded into the convective-microwave zone was also studied. Calculations were made for the grain moisture content range of \(W=14\%\) to 26%. It is precisely within this moisture content range that the grain is exposed to the effect of the microwave field in the processing area. The results of the studies are listed in Table 2.  
The data listed in Table 2 show that none of the resonance frequency modes are identical to that of the magnetron. \(Q\)-factor values for resonance frequencies closely adjacent to the magnetron's fundamental frequency vary in the range from 0.8173 to 6.949 for various modes. Moreover, they differ substantially even for the same grain's moisture content value. This is easily explicable since a number of different wave types participate in the process of microwave energy transfer, and their resonance frequencies change depending on varying dielectric properties of materials present in the processing zone. That is why radiation efficiency changes as well, as noted above.