# 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
Additionally, 227 \(\Omega\) and 14 \(\Omega\) were calculated as the respective impedances of the inductor and capacitor. Regarding the design frequency, 6 GHz was chosen for the MOSFET-based absorber. Values of inductors and capacitors for the MOSFET-based absorber can be computed as:  
\[L=\frac{X_{L}}{2\pi f} \tag{10}\]  
\[C=\frac{1}{2\pi fX_{C}} \tag{11}\]  
The values of the inductor (\(L\)) and capacitor (C\({}_{4}\) and C\({}_{5}\)) were calculated as 8 nH and 2.5 pF, respectively. The load resistor (\(R_{2}\)) used in the MOSFET-based absorber was computed as a function of the voltage and current component of the peak reflected power, as shown in Equation (12), and the value is 157 k\(\Omega\). \[V_{rms}=V_{peak}\times 0.707 \tag{3}\]0  
The MOSFET-based absorber schematic is presented in \[V_{rms}=V_{peak}\times 0.707 \tag{3}\]1 In order to complete the rectification process while taking into account the ON and OFF states of the diodes and the potentials at each node of the rectifier, it has been demonstrated that the absorber is a combination of an RLC filter, an N-channel MOSFET, and a four-diode combination [55; 56; 57]. The function of the RLC filter, in this case, is to reduce the pulses at the output of the rectifier; this allows for maximum performance of the MOSFET device in the absorber. To turn ON the MOSFET, a DC voltage (V\({}_{G}\)) of 12 V is applied to the MOSFET gate, thus allowing the flow of the current from the drain to the source. Figure 13 shows the 3D EM/circuit co-simulation schematic of the integrated SiO\({}_{2}\) MOSFET-based absorber and dual-band double-material substrate CSPA. To run the co-simulated schematic, the output of the pulse generator was connected to port-1 of the presented schematic (Figure 13). The reflected power resulting from the mismatch between the pulse generator (PA) and the DMS CSPA is rectified, filtered, and observed at P11 (drain terminal of the MOSFET) and P10 (source terminal of the MOSFET). In the proposed MOSFET-based absorber integrated antenna model, reflection is bound to occur from the antenna branch (port-2) under two MOSFET source current (Is) operation conditions. The condition for MOSFET absorption has been used from Refs. [53; 54; 55; 56]. \[V_{rms}=V_{peak}\times 0.707 \tag{3}\]2 Designed MOSFET-based absorber. \[V_{rms}=V_{peak}\times 0.707 \tag{3}\]3 Proposed MOSFET-based absorber integrated antenna. After running a transient simulation on the presented schematic of the MOSFET-based absorber antenna, the drain voltage and current were observed as in \[V_{rms}=V_{peak}\times 0.707 \tag{3}\]4 Considering the proposed antenna, the MOSFET-based absorber serves its purpose of absorbing the reflected signal from the antenna branch of the circulator, if the relationships \(I_{S}\leq I_{D}\) (current at P10 greater than or equal to current at p11) and \(V_{DS}=0\) (voltage at p10 equal to 0) are justified. When these conditions are satisfied, adverse effects (such as aching within the transmission line or signal route within the circulator) are eliminated from a mismatch between the PA and the antenna. From Table 4, it is observed that the condition for MOSFET absorption is satisfied for the designed antenna (source voltage is 0 and the source current is negative compared to the drain current, implying a condition of \(I_{S}\leq I_{D}\)).