## 6 Results
- The maximum SE values reached for each of the better shielding materials are as follows: BW achieves 16.2 dB, BW-MW achieves 18 dB, and concrete wall achieves 19.7 dB. These maxima occur at the higher end of the measured frequency range, emphasizing that these materials perform better at higher frequencies. - The overall trend observed is that the shielding effectiveness of all materials increases with frequency, but the rate of increase and the absolute values of SE are highly material-dependent. The materials designed for shielding (BW, BW-MW, concrete wall) show a significant increase in effectiveness, particularly in the higher frequency range. Further investigation was conducted on the reflection of electromagnetic waves for the observed materials. The results of the electromagnetic wave reflection measurements are presented in Figure 8. The measurement outcomes indicate the materials' property to reflect electromagnetic waves. Several conclusions can be drawn from the trends shown in Figure 8:  
The materials MW (mineral wool), PT (hardened polystyrene), PE (extruded polystyrene), and PUR board (polyurethane board) exhibit the lowest values of electromagnetic wave reflection (\(R\)). This observation correlates with their low shielding effectiveness (\(SE\)) as previously discussed, supporting the hypothesis that materials with lower SE also demonstrate lower reflection characteristics. Figure 8: Dependence of reflection of electromagnetic wave for MW, PT, PE, PUR board, concrete wall, BW, and BW-MW. Conversely, the materials BW (brick wall), BW-MW (brick wall filled with mineral wool), and concrete wall show the highest values of reflection in the observed frequency range. This finding is consistent with the earlier conclusion that these materials offer higher SE. The trend in the development of electromagnetic wave reflection over the observed frequency range is similar across all three materials. Similar to the SE behavior, for the material BW, the reflection (\(R\)) values in the frequency range from 6 GHz to 9 GHz remain stable, indicating that the material's reflective properties do not change significantly within this band. The ratio between the SE values for materials MW, PT, PE, and PUR board and those for materials BW, BW-MW, and concrete wall is higher than the ratio between the R values. This suggests that the impact of material properties on SE is more pronounced than that on R, indicating that other factors such as absorption and transmission losses may contribute more significantly to SE than to reflection alone. The maximum reflection (\(R\)) values for the materials are as follows: for BW, it is 7 dB; for BW-MW, it is 8 dB; and for concrete wall, it is 9 dB. These maximum values reinforce the concept that materials with higher density and structural complexity, such as concrete walls and brick walls filled with mineral wool, are more effective in reflecting electromagnetic waves, especially at higher frequencies. These conclusions support and extend the understanding of the materials' interaction with electromagnetic waves, emphasizing the importance of considering both \(SE\) and reflection when assessing a material's shielding capabilities. In the final step, the value of the electromagnetic wave absorption (\(A\)) was calculated. The absorption values were computed according to Equation (27). \[SE=A+R\] (27) The dependencies of the electromagnetic wave absorption for all the examined materials can be seen in Figure 9. From the dependencies, the following observations can be made: In the observed frequency range from 1 GHz to 9 GHz, there is an increasing trend in the electromagnetic wave absorption (\(A\)) for the materials BW (brick wall), BW-MW and the composite wall (\(A\)) for the materials BW (brick wall), BW-MW and the composite wall (\(A\)) for the materials BW (brick wall), BW-MW and the composite wall (\(A\)) for the materials BW (brick wall), BW-MW and the composite wall (\(A\)) for the composite wall (\(A\(brick wall filled with mineral wool), and concrete wall.