## 3 Results and Discussion
### Measurements of NiO/PANI/ZnNb\({}_{2}\)O\({}_{6}\) Composite's EMI Shielding Effect
It is understood that the effective values of microwave shielding are closely related to the alignment of the irradiation impedance with the surface of the material. The presence of the conductive polymer PANI caused the emergence of distinct peaks in shielding efficiency together with the resonance effect. This conductive polymer not only contributes to these sharp peaks, but also strengthens them. Significant value is added to the electromagnetic shielding composite material by the interface polarization between polyaniline and (NiO-ZnNb\({}_{2}\)O\({}_{6}\)). The interplay of the trap shape and the resonance effect of reflection is responsible for the observed peaks in shielding efficiency. \begin{table}
\begin{tabular}{l c c c} \hline \hline \multirow{2}{*}{**Samples**} & **Shielding Effectiveness** & \multirow{2}{*}{**Frequency**} & \multirow{2}{*}{**Reference**} \\  & **Value** & & \\ \hline NiFe\({}_{1,7}\)Cu\({}_{0,3}\)O\({}_{3.85}\)/Aniline: 1/3 & \(-\)29.74 dB & 6.82 GHz & [2] \\ \hline \% 25 MWCNT & \(-\)39 dB & 1.6 GHz & [22] \\ \hline Chopped strands/Ba(Zn\({}_{1/3}\)Nb\({}_{2/3}\))O\({}_{3}\) (at 20–80 wt. \%) & \(-\)24.96 dB & 6.22 GHz & [1] \\ \hline Epoxy-(NiO/PANI/ZnNb\({}_{2}\)O\({}_{6}\)) & \(-\)41.16 dB & 6.24 GHz & This work \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Other results in the literature for the efficiency of microwave shielding. Additionally, the material's electrical losses due to the conductive polymer PANI help to fine-tune the ZnNb\({}_{2}\)O\({}_{6}\) structure's dielectric shielding effect, increasing the electromagnetic shielding efficacy in the process. The shielding efficacy values for epoxy-based (NiO/polyaniline/ZnNb\({}_{2}\)O\({}_{6}\)) composites across the GHz range are shown in Table 3.  
Microstructural Influence on Shielding Performance  
The shielding effectiveness (SE) of NiO/PANI/ZnNb\({}_{2}\)O\({}_{6}\) composites is closely linked to their microstructural characteristics, as revealed by SEM and XRD analyses. The NiO:ZnNb\({}_{2}\)O\({}_{6}\) (25-75 wt. %)/PANI (1/1) composite exhibited moderate SE (\(-\)35.3 dB at 6.24 GHz), primarily due to its ZnNb\({}_{2}\)O\({}_{6}\)-rich phase, which enhanced dielectric polarization losses but had limited conductivity. Increasing the NiO content to a 50-50 ratio improved the conductive network and interfacial polarization, resulting in a slightly higher SE (\(-\)33.94 dB at 5.64 GHz). The best performance was observed in the NiO:ZnNb\({}_{2}\)O\({}_{6}\) (75-25 wt. %)/PANI (1/1) composite, which achieved \(-\)41.16 dB at 6.24 GHz due to its well-connected NiO conductive pathways, improved impedance matching, and multiple scattering effects facilitated by PANI. The shielding mechanisms across all samples involved a combination of reflection, absorption, and internal scattering, with NiO enhancing conductivity and reflection, ZnNb\({}_{2}\)O\({}_{6}\) contributing to dielectric loss, and PANI improving charge transport and absorption. These findings highlight that optimizing the NiO:ZnNb\({}_{2}\)O\({}_{6}\) ratio is key to achieving superior EMI shielding performance, making these composites promising candidates for sub-8 GHz applications. The proposed material offers a cost advantage due to the use of inexpensive raw materials, energy-efficient processing, and minimal maintenance compared to traditional metal-based shielding (the estimated price is USD 0.15/cm\({}^{3}\)). Additionally, its durability contributes to long-term cost savings.