At present, an important task is to determine the burning rate of energy condensed systems (ECS) with metal additives under non-stationary conditions. At the same time, a promising way to experimentally determine the law of the burning rate is the radio wave microwave method. However, the presence of a significant amount of condensed phase in the combustion products of metallized ECS complicates the tuning of the interference microwave diagnostic method. The article considers the interaction of an incident monochromatic electromagnetic wave with a single particle of the condensed phase in a closed volume without taking into account the influence of the result of the interaction of other particles with the incident wave. A mathematical model has been developed and scattering indicatrices have been obtained for various particle diameters in the range from 10 to 20 micrometers, generated radiation frequencies in the range of 9–15 GHz, and permittivities of condensed-phase particles in the range of 1.6–10. An analysis of the results of a numerical study demonstrates that an increase in the particle size leads to a sharp increase in the intensity of the scattered wave. Changing the frequency of the wave generated by the microwave generator is a priority method for amplifying the intensity of the scattered wave, which makes it possible to detect particles with smaller diameters up to several micrometers.