## 5 Conclusions  
The presented results clearly confirm that microwave resonant chambers necessary for technical applications may be efficiently modelled on the base of open-source software  
Figure 8: Chamber radius \(R\) dependence of maximal values of electromagnetic field strength \(H\) for a microwave chamber in a resonant state. Plots calculated for different values of model mesh granularity \(h_{max}\).  
Figure 7: Mesh granularity \(h_{max}\) dependence of electromagnetic field strength \(H\) distributions in resonance. Resonance occurs for different values of microwave resonant chamber radius \(R\).  
tool chains covering mainly NETGEN mesher, ELMER FEM finite elements solver as well as PARAVIEW visualization software.  
It should be highlighted that the results of finite elements modelling of resonant chamber diameters significantly vary from the results achieved on the base of commonly known, generalized and simplified equations. This is connected with the fact that shapes of resonant chambers used in practice significantly vary from simplified theoretical shapes and can be influenced by, e.g., connected waveguides.  
On the other hand, mesh granularity, described by the maximal height of tetrahedral element \(h_{max}\), may significantly influence the results of modelling. The present article proposed an iterative method of modelling while decreasing the granularity parameter \(h_{max}\). With the use of this proposed method, the resonant chamber's dimensions may be determined with the required degree of accuracy; additionally, one can avoid overcoming the computing power and memory resources of the available computer.  
In addition, due to spatial averaging during the finite element method, the height of tetrahedral elements can be much bigger than the accuracy of estimation of the geometry of the resonant chamber. This effect is very useful in the case of development and modelling of microwave resonant chambers for practical applications.  
It should be highlighted that modelling microwave chambers and cavities in a resonant state is a diversified task. The present paper presents a specific example as well as a concept of a universal method of identification of the parameters of geometry of such chambers, especially microwave chambers for drying equipment. Further works should be focused on microwave chemistry and miniature microwave resonant chambers for materials physics research. In such a case, a material located in the resonant chamber or cavity can significantly influence the resonant condition. Such an influence may be also modelled, enabling optimization of functional parameters of resonant chambers or miniature cavities according to the needs of the microwave chemistry of given physical processes.  
Conceptualization, D.K., A.O.-L. and R.S.; methodology, A.O.-L., D.K., P.R.; software, D.K., P.R., A.O.-L. and P.R.; validation, J.S.; formal analysis, D.K.; investigation, D.K., A.O.-L. and R.S.; data curation, D.K. and A.O.-L.; writing--original draft preparation, D.K., A.O.-L. and R.S.; writing--review and editing, D.K., A.O.-L., J.S., P.R. and R.S.; visualization, D.K. and A.O.-L.; supervision, A.O.-L. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.