## 6 Results  
To prevent interference signals, the measurement was conducted in an anechoic chamber. Prior to the measurement, calibration of the workstation was performed according to Equation (23). After the calibration was completed, a frequency of 1 GHz was set on the transmitting antenna. Using the receiving antenna and spectrum analyzer, the signal at the receiving antenna was recorded. The frequency was incrementally increased by 0.1 GHz up \begin{table}
\begin{tabular}{c c c} \hline \hline
**Source of Measurement Uncertainty** & \(K\) & **Uncertainty Value [dB]** \\ \hline Relative amplitude accuracy of the spectrum analyzer & \(\sqrt{3}\) & 0.6 \\ \hline Amplitude stability of the signal source & \(\sqrt{3}\) & 0.02 \\ \hline Errors occurring during transmission & \(\sqrt{2}\) & 0.06 \\ \hline Errors occurring during reception & \(\sqrt{2}\) & 0.06 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: List of sources of measurement uncertainty [4]. to a value of 9 GHz. After the measurement without shielding was completed, a measured object was placed between the receiving and transmitting antennas. The frequency of 1 GHz and signal height were set again on the transmitting antenna. This signal was captured using the receiving antenna and displayed with the spectrum analyzer. The final step involved calculating the shielding effectiveness based on Equation (18), using the results from the measurements with and without shielding. The same method was used to measure the shielding effectiveness for all shielding materials. The following building materials were examined, each with a thickness of 30 cm:  
- Mineral wool--\"MW\". - Hardened polystyrene--\"PT\". - Extruded polystyrene--\"PE\". - PUR board. - Concrete wall--\"Concrete-wall\". - Brick--\"BW\". - Brick filled with mineral wool--\"BW-MW\". The research results are displayed in Figure 7. From the results, it is apparent that the materials MW, PT, PE, and PUR board achieve the lowest shielding effectiveness values. Among these four materials, the PUR board achieves the highest values. The materials MW, PT, PE, and PUR board reach values at the level of measurement uncertainty. In this case, it is not possible to demonstrate the shielding capability of the materials against electromagnetic waves. The materials BW, BW-MW, and concrete wall achieve significantly higher shielding effectiveness values. In the observed frequency band, it holds that with increasing frequency, the value of shielding effectiveness also increases. When comparing the materials BW, BW-MW, and concrete wall, the following conclusions can be drawn:  
* The graph shows a clear distinction in the shielding effectiveness (_SE_) across the different materials. Materials such as MW (mineral wool), PT (hardened polystyrene), PE (extruded polystyrene), and PUR board (polyurethane board) demonstrate low SE values throughout the entire frequency range, with all these materials' SE values hovering around the measurement uncertainty level. Figure 7: Dependence of shielding effectiveness for MW, PT, PE, PUR board, concrete wall, BW, and BW-MW. The PUR board shows a slightly higher SE than the other low-effectiveness materials, although it still remains significantly lower compared to the materials designed for better shielding. - The SE for the material BW (brick wall) exhibits a plateau effect in the frequency range from 6 GHz to 9 GHz, indicating that the shielding effectiveness does not significantly change within this band. - On the other hand, the materials BW-MW (brick wall filled with mineral wool) and concrete wall show a consistent increase in shielding effectiveness up to 9 GHz, which suggests that these materials have a better capability to shield against higher frequency electromagnetic waves. - In comparing BW-MW and concrete wall, their SE trends are nearly identical, and their values are almost the same across the frequency spectrum, highlighting their similar shielding properties.