# Testing and Analysis of MOSFET-Based Absorber Integrated Antenna for 5G/WiMAX/WLAN Applications
## 4 Electromagnetic Circuit Simulation Analysis of MOSFET-Based Absorber Integrated Antenna  
The absorbers are classified as broadband absorbers or narrowband absorbers [46; 47]. Broadband absorbers work across a large frequency range, but typically exhibit low levels of attenuation, whereas narrowband absorbers work well over a smaller frequency range but exhibit high levels of attenuation [48]. [PERSON] et al. [49] developed a novel downsized absorber frequency selective surface for low-frequency transmission/high-frequency absorption. In this instance, the lower layer's selection zone of the symmetrical frequency was below 1.8 GHz, and the wave transmission rate was more than 84%. A wave-absorbing frequency selective surface (AFSS) with low-frequency transmission and high-frequency absorption was proposed by [PERSON] et al. [50]. To prevent the frequency selection feature from affecting the microwave absorption effect, the unit uses a method that loads the frequency selection structure proportionally to the absorber's reflective metal surface. The suggested model offered more than 10 dB insertion loss between 4 GHz and 5.5 GHz. [PERSON] et al. [51] designed and optimized an absorber design for the C-band using equivalent circuit analysis. Capacitive and analog circuit layers with lumped resistors make up the design. The entire wave simulation of the constructed microwave absorber displays a bandwidth of below \(-10\) dB absorption from 4.23 GHz to 8.13 GHz. Although most absorbers are foam absorbers, depending on the frequency needed and the level of absorption they can deliver, they could also be analog circuits [52]. For a MOSFET-based absorber design, it is vital to know the amount of predicted reflected power from the antenna branch of the proposed MOSFET-based antenna design. Knowledge of the peak and RMS values of current, voltage, and power will enable engineers to analyze the proper values of resistors, capacitors, and inductors (resistor inductor-capacitor filter) for the MOSFET-based absorber design [53]. To compute these values, port-1 of the circulator presented in Section 2 is connected to the SRD pulse generator's output, and port-2 of the circulator is connected to the DMS dual-band antenna. After carrying out a transient 3D EM/co-simulation of the connected device, the reflected peak current and peak voltage from the antenna branch are observed at port-3, with values of 4.36 mA and 722 mV, respectively, as shown in Figure 11a,b. Figure 11: Circulator port after antenna attachment. (**a**) Current and (**b**) voltage. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ports** & **Current** & **Voltage** & **Power** \\  & **(mA)** & **(mV)** & **(mW)** \\ \hline
1 & 26.9 & 2623 & 70,559 \\ \hline
2 & 18.9 & 2100 & 39,690 \\ \hline
3 & 0.8 & 240 & 192 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Circulator port parameters. Equations (3) through (12) have been adopted from the existing literature [3; 53; 54; 55; 56; 57]:  
\[V_{rms}=V_{peak}\times 0.707 \tag{3}\]  
\[V_{DC}=\frac{2V_{peak}}{\pi} \tag{4}\]  
\[I_{rms}=0.707\times I_{peak} \tag{5}\]  
\[I_{DC}=\frac{2I_{peak}}{\pi} \tag{6}\]  
Using Equations (3) and (6), the rms and DC values of reflected current and voltage signals have been computed as \(V_{rms}\) (495 mV), \(I_{rms}\) (3.08 mA), \(V_{dc}\) (446 mV), and \(I_{dc}\) (2.8 mA). In addition, the ripple factor and impedance of the inductor (\(X_{L}\)) and capacitor (\(X_{C}\)) influence the capacitor and inductor values required for the MOSFET absorber design. The ripple factor, the impedance of the inductor, and the impedance of the capacitor are defined as:  
\[RippleFactor=\frac{\sqrt{I_{rms}^{2}-I_{DC}^{2}}}{I_{DC}} \tag{7}\]  
\[X_{L}=\frac{V_{peak}}{I_{rms}} \tag{8}\]  
\[X_{C}=\sqrt{\frac{3X_{L}\times Ripple\ factor}{\sqrt{2}}} \tag{9}\]  
The ripple factor increases to 0.46 when these values for \(I_{rms}\) and \(I_{DC}\) are substituted into Equation (7).