## 4 Conclusions  
Our studies based on the results of computer modeling using the software package CST have led us to the following conclusions:  
* Studies of the directional diagrams show that the pattern of microwave electromagnetic field propagation in a grain layer changes depending on the moisture content of the grain under processing. Both the radiation amplitude and the grain layer's coverage area by radiation undergo changes.
* Changes in the moisture content of the grain under processing in the microwave-active zone result in a 15.1% growth in radiation efficiency of the waveguides (from 58.294 dB to 68.729 dB), as the moisture content decreases from 26% to 14%. The total radiation efficiency also increases (from -21.7 dB to -11.27 dB). Furthermore, not only does the value of the radiation efficiency change, but also the shape of its characteristic changes for different magnetron radiation frequencies. The obtained data indicate that the loss of microwave energy in a waveguide increases with the moisture content in the grain under processing.
* Changes in the moisture content of the grain present in a microwave-active zone result in changes to the level of exposure and their maximum orientation, both along the waveguide and in relation to the radiating surface. The degree of uniformity in the radiation distribution along the waveguide also changes.
* Studying the effect of the specific design features of the microwave-active zone's design structure and the moisture content in the grain under processing has clarified that the \(Q\)-factor of a grain treatment area significantly depends on its specific design and the arrangement of technological components inside it. Variations in the moisture content of the grain subject to processing and its temperature have a strong effect on the \(Q\)-factor value. Therefore, the \(Q\)-factor plays only a secondary role, and there is no practical reason to take it into account when calculating microwave-active zones.  
The obtained results can serve as a basis for designing microwave-active zones and developing operation algorithms for technological units used in grain processing using the convective-microwave method.  
The above allows formulating potential directions for further research:  
First and foremost, it is necessary to evaluate the options for matching waveguides with the load. To what extent do existing approaches allow them to be applied to microwave-convection grain processing installations? In doing so, consider new options for such matching.  
Research is needed to what extent changes in the moisture content of the processed grain affect energy consumption and to what extent it needs to be considered in real microwave-convection grain processing installations.  
To increase drying efficiency, it is advisable to consider options for optimal process management, taking into account the research results obtained.  
Conceptualization, A.N.V.; methodology, D.B.; software, validation, formal analysis, A.A.V., A.N.V. and D.B.; investigation, A.A.V. and D.T.; resources, data curation, A.N.V. and D.T.; writing--original draft preparation, writing--review and editing, visualization, A.A.V. and D.T.; supervision, project administration, A.N.V.; funding acquisition, A.A.V. All authors have read and agreed to the published version of the manuscript.  
This research was supported by Federal Scientific Agroengineering Center VIM (RF state assignment No FGUN-2022-0004).  
Not applicable.  
Data Availability Statement: The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest.