# Monitoring of Surgically Treated Upper Arm Fracture by Implanted Antenna at 402 MHz
## 4 Simulation and Discussion
\begin{table}
\begin{tabular}{c c c c} \hline
**Antenna Parameter** & **Dimension in mm** & **Antenna Parameter** & **Dimension in mm** \\ \hline Radiator length & 111 & Substrate length & 116 \\ Radiator width & 1 & Substrate width & 5 \\ Radiator thickness & 0.035 & Substrate thickness & 0.5 \\ Gap & 1 & Coating thickness & 0.1 \\ Trace width & 1 & & \\ \hline \end{tabular}
\end{table} 
Table 5: Antenna dimensions within human tissue. Figure 7: _Cont._  
The simulation of S11, which provides information about the power reflected back from the antenna, shows \(-38.15\) dB in the case of normal bone and \(-15.8\) dB, \(-16.5\) dB, and \(-15.5\) dB for the transverse, \(30^{\circ}\) and \(60^{\circ}\) oblique fractures, respectively. Figure 9 shows the return loss in cases of normal and the studied types of upper arm fractures. Figure 7: Three-dimensional and planar far-field pattern of the antenna (**a**) in air and (**b**) in tissue. (**c**) Realized gain in tissue and (**d**) variation in realized gain and total efficiency with frequency. From the geometry of the 3D pattern shown in Figure 7b, we select to test the change in the transmitted APDs at two constant \(\Phi\) at \(\pm 90^{\circ}\), in which the transmitted APD is at its greatest value. At these two positions, the difference between the transmitted APD in cases of a normal and fractured bone also experiences a considerable value. Figure 10 shows the electric field distribution and a comparison between the transmitted APD at a distance of 30 cm in the far-field of the antenna for the normal and fractured humerus. This observation is recorded at constant values \(\pm 90^{\circ}\) of \(\Phi\) angle at which the maximum transmitted power is obtained. The result of this comparison represents the healing status. The results for transverse fracture, \(30^{\circ}\) and \(60^{\circ}\) oblique fractures at the points of maximum transmission were considered. Table 6 provides a comparative result of the transmitted APD in the normal and fractured humerus. The greater the difference between the transmitted APD outside the body in cases of normal bone and fractured bone, the better the monitoring of the bone healing status. The transmission at \(\Phi=90^{\circ}\) for normal and fractured humerus' is greater than that at \(\Phi=-90^{\circ}\). This is due to the shorter distance that the radiation passes in the lossy tissue medium as this direction excludes propagation through the bone and transmission through the muscle, fat, and skin to the air outside the body. This shorter path saves 27.2% of the transmitted power density. The percentage reduction in transmission due to the fractures is comparable at two values \(\pm\) 90\({}^{\circ}\) of \(\Phi\). Figure 8: Simulated SAR in tissue. Figure 9: S parameter for normal and fractured humerus. Figure 10: The electric field distribution; (**a**) variation in transmitted APD at (**b**) \(\Phi=\)90\({}^{\circ}\) and (**c**) \(\Phi=-\)90\({}^{\circ}\) for the normal humerus, transverse fractured humerus and 30\({}^{\circ}\) and 60\({}^{\circ}\) oblique fractured humerus.