## 3 Results  
### Microwave Field Directional Diagrams for Grains of Various Moisture Content  
For ease of analysis, radiation directional diagrams for Phi = 0\({}^{\circ}\) are presented in linear form (Figures 4 and 5). This directional diagram is shown in the angle range from 0\({}^{\circ}\) to 180\({}^{\circ}\). It presents the distribution of the microwave field emitted from the slot radiators directly into a grain layer. In the case of linear representation, the entire waveguide length is divided into 180\({}^{\circ}\). For a 400 mm long waveguide, one angular degree corresponds to 2.2 mm. Figure 4: Radiation directional diagram of the waveguide, for grain wheat having moisture content of 14% and 16%. Figure 5: Radiation directional diagram of the waveguide, for grain wheat having moisture content of 20% and 26%. Our analysis of the directional diagrams made it possible to conclude the following. The maximum values on the directional diagrams for microwave radiation change their position depending on the moisture content in the grain under processing. These positions of radiation maxima are shown in Figures by dashed vertical lines. Thus, for wheat grain with a moisture content of 14% and 16%, they correspond to 32\({}^{\circ}\) (9,62 dBi) and 16\({}^{\circ}\) (9,14 dBi), respectively, which are close to the radiation source. Conversely, for grain with a moisture content of 26%, the radiation maximum corresponds to 175\({}^{\circ}\), i.e., it is located in the area close to the far end of the waveguide, in relation to the radiation source. This conclusion is essentially important since it enables us to analyze changes in the electromagnetic field orientation within the convective-microwave zone depending on the moisture content in the grain. It follows from these directional diagrams that the area of maximum radiation intensity will drift along the waveguide, thus preventing grain overheating in only one particular waveguide's internal volume. Furthermore, our analysis of the directional diagrams shows that the distribution uniformity of the microwave field intensity along the waveguide is better for grain containing 20% to 26% moisture compared to that having 16% to 14% moisture content. Microwave radiation power is lower for grain containing 20% to 26% moisture, and its distribution uniformity is better, with the exception of small areas inside the waveguide close to its middle. This gives us a reason to suggest that by drying grain with an initial moisture content exceeding 20%, we can avoid its overheating in any section of the electromagnetic field along the waveguide's axis. At the same time, processing grain (for instance, presowing treatment) with moisture content close to its standard value (14%) is associated with the risk of such local overheating. Therefore, this feature has to be taken into account while defining the technological conditions of grain processing, or relevant modifications have to be introduced into the convective-microwave zone's design structure. Radiation directional diagrams for Theta = 90\({}^{\circ}\) are shown in Figure 6.  
Figure 6: Radiation directional diagrams of microwave field, for angle Theta = 90\({}^{\circ}\): (**a**) microwave radiation directivity in a grain layer having moisture content of 14%; (**b**) microwave radiation directivity in a grain layer having moisture content 26%. The directional diagram presented in Figure 6 shows that the pattern of the microwave electromagnetic field propagation changes depending on the moisture content in the grain during processing. While for a moisture content of 14% (Figure 6a), the maximum radiation is directed towards the lower part of the waveguide at an angle of 45\({}^{\circ}\), for the grain moisture content of 26% (Figure 6b), this angle equals 0\({}^{\circ}\). Clearly, both the amplitude and the grain layer area covered by radiation undergo changes.