## 3 Results and Discussions
### Time-Domain SE of Different Materials  
Figure 6 shows the calculated electric field at observation point in chassis 2 under different polarization modes, with the angle of the incident wave set as \(\varphi_{i}=0^{\circ}\) and \(\theta_{i}=90^{\circ}\), respectively. Figure 6a is the result of the calculation of the horizontal polarization, and Figure 6b is the vertical polarization.  
The results show that the electric fields at the observation points are different for all three materials under different polarization modes. It can be seen that the peak electric field at the observation point in the carbon fiber chassis is the highest and the TDSE is the lowest, regardless of vertical or horizontal polarization. The peak electric field of the metal chassis is smaller than that of the carbon fiber chassis and larger than that of the nickel-plated carbon fiber chassis. This is because when electromagnetic waves are coupled into the chassis, the high conductivity of the stainless steel generates a strong impedance mismatch with the air, resulting in strong reflected waves. For nickel-plated carbon fiber chassis, the high conductivity of the outermost layer of nickel can effectively reflect electromagnetic waves. At the same time, from the inside of the chassis to the outside of the formation of an \"air-carbon fiber-nickel\" structure, this conductivity gradient increases the asymmetric structure and can effectively improve the impedance mismatch problem to alleviate the reflection of electromagnetic waves inside the chassis. Finally, the nickel-plated layer has good magnetic properties, which can further absorb the electromagnetic wave reflected to the nickel-plated layer inside the chassis. Thus, the peak electric field inside the chassis decreases significantly. Therefore, the nickel-plated carbon fiber chassis has the highest time-domain shielding effectiveness.  
To further illustrate the advantages of nickel-plated carbon fiber materials, we performed simulations in a double-layer shielded chassis with different aperture array structures. The aperture arrays on the inner shielding chambers are set according to Table 1, and the calculation results are shown in Figure 7, where Figure 7a shows the calculation results for horizontal polarization and Figure 7b shows the calculation results for vertical polarization.  
As can be seen in Figure 7, the peak electric field is reduced at each observation point, which proves the good shielding performance of the composite. The comparative SE\({}_{\text{PR}}\) of each material's chassis, as a function of varying different hole array structures and polarization modes, are systematically tabulated in Table 2. Additionally, to contextualize the relative weights of the three materials' chassis, their densities are enumerated within the table, where \(\alpha\) denotes the polarization angle. From Table 3, it can be seen that the time-domain shielding effectiveness of the nickel-plated carbon fiber double-layer shielding chassis is better than that of the carbon fiber double-layer shielding chassis and the metal double-layer shielding chassis, and in terms of weight, the weight reduction of the nickel  
Figure 6: Variation in electric field with time at the chassis observation point: (**a**) horizontal polarization; (**b**) vertical polarization.  
plated carbon fiber chassis compared with the stainless steel-metal chassis can be as high as 71.43-76.25%.  
This meticulous examination, embodied in the simulation results, accentuates the nuanced differences in shielding effectiveness amongst the materials tested, highlighting the composite material's superior performance in mitigating electromagnetic interference. The findings affirm the potential of nickel-plated carbon fiber composites as lightweight yet effective shielding solutions, thereby paving the way for their application in domains where both weight efficiency and electromagnetic protection are paramount.