Silicon carbide fiber reinforced silicon carbide matrix composites (SiCf/SiC) have been identified as a material with high-performance mechanical properties for the aerospace industry. Microwave-enhanced (ME) chemical vapor infiltration (CVI) heating of ceramic matrix has been proposed as an efficient production technique having the potential to yield near fully dense SiCf/SiC composites in a significantly shorter time span. This paper presents some results of computational analysis of electromagnetic and thermal characteristics of the ME CVI process carried out with thin SiC discs in a Labotron microwave system from SAIREM. The simulations are aimed to clarify multiple unexplained observations in experimental work through understanding causes for the formation of microwave-induced temperature fields. Resonant and non-resonant frequencies of the experimental system for different temperatures of the processed SiC sample are analyzed to explain the difference in heating rates. 3D temperature fields in the SiC preforms at different frequencies are also presented. It is shown that, after being non-uniform in the beginning of the process, temperature patterns evolve to quite homogeneous ones by its end. The results suggest a means for better control of the equipment to pave the way to more efficient implementations of ME CVI the hence the less expensive and high quality SiCf/SiC composites.