## 3 Results and Discussion  
The results of the simulation illustrate that the conductivity of VO\({}_{2}\) in the metallic phase reaches a level of 2 \(\times\) 10\({}^{5}\) S/m, enhancing the absorber's capacity for wideband absorption. Remarkably, the absorption performance is within the range of 2.4 THz to 11 THz. We introduce \(f_{\text{L}}=2.4\) THz and \(f_{\text{H}}=11\) THz into the formula \(ff_{oc}=2\frac{f_{\text{H}}-f_{\text{L}}}{f_{\text{H}}+f_{\text{L}}}\), and we can obtain a relative bandwidth of 128.4%. The absorption levels surpass 99% at the resonance point of 3.0 THz, 7.1 THz, 8.7 THz, and 10.6 THz, achieving perfect absorption. When VO\({}_{2}\) is in the insulating phase, the conductivity is 200 S/m, the absorbed amount is below 2%, while the reflection surpasses 98%. By adjusting the conductivity of VO\({}_{2}\) from 200,000 S/m to 200 S/m, the property of VO\({}_{2}\) changes from a metallic state to an insulating state, and a transformation occurs in the behavior of the absorber. Illustrated in Figure 2, it is evident that control over the absorber's absorption and reflection is highly precise and dynamic. With the ability to manipulate both parameters within the absorption bandwidth, the ability to toggle between absorption and reflection based on specific operational needs is made possible. It is worth mentioning that, in VO\({}_{2}\) metamaterial absorbers, when the temperature fluctuates within the transition zone, the conductivity of the VO\({}_{2}\) film also changes accordingly. This change may cause a shift in the threshold frequency of the absorber, thereby altering the position and width of the absorption bandwidth. In addition, temperature fluctuations may also affect the transmission characteristics of VO\({}_{2}\) thin films, thereby affecting their absorption capacity at specific frequencies. As a result, the capability of VO\({}_{2}\) in absorption tuning lies in the manipulation of conductivity through temperature variations within the terahertz range, offering increased versatility and adaptability for practical applications, increasing the versatility and functionality of the equipment. Figure 2: Cont. The theory of impedance matching is employed to clarify the physical mechanism behind achieving broadband perfect absorption. Equation (3) can be used to represent the relative impedance of the absorber:  
\[Z=\sqrt{\frac{\mu}{\varepsilon}}=\sqrt{\frac{\left(1+S_{11}\right)^{2}-S_{21}^{2 }}{\left(1-S_{11}\right)^{2}-S_{21}^{2}}} \tag{3}\]  
The magnetic permeability represented by \(\mu\) and the dielectric constant represented by \(\varepsilon\) appear in Equation (3). Through simulation, \(S_{11}\) and \(S_{21}\) can be derived. As a result, the S-parameter inversion method can be used to determine both the real and imaginary components of the absorber's relative impedance. The correlation between the capacity to absorb and the relative impedance is demonstrated by the following equation:  
\[A(\omega)=1-\mathrm{R}(\omega)=1-\left|\frac{Z-Z_{0}}{Z+Z_{0}}\right|^{2}=1- \left|\frac{Z_{r}-1}{Z_{r}+1}\right|^{2} \tag{4}\]  
In Equation (4), \(Z_{0}\) is the effective impedance of the surrounding environment, the impedance value is effectively controlled by the absorber, and \(Z_{r}=Z/Z_{0}\) is the relative impedance between the absorber and air. When the effective impedance of the absorber matches the relative impedance of air, \(Z_{r}\) is equal to 1; thus, achieving ideal absorption is possible for the absorber. By evaluating the absorption spectrum and the real and imaginary components of the relative impedance using \(S_{11}\) and \(S_{21}\) with varying phases of VO\  
to adapt its properties between absorption and reflection modes depending on different operational conditions, thereby enhancing its versatility and adjustability.