# A Small Implantable Compact Antenna for Wireless Telemetry Applied to Wireless Body Area Networks
## 4 Discussion
### Wireless Data Transmission Verification  
The antenna's capability to achieve stable data transmission was further experimentally verified using the setup depicted in Figure 17. As shown, one end of the experimental setup consists of an antenna implanted into pork tissue and a Nano Pi Duo2 development board (FriendlyElec, Guangzhou, China) forming a wireless module, while the other end utilizes a common wireless router for data transmission. To comprehensively assess the wireless data transmission capabilities of the implantable antenna, experiments were conducted with the implantable antenna serving both as the receiver and the transmitter.  
Figure 16: Link margin analysis for the proposed antenna.  
\begin{table}
\begin{tabular}{c c c} \hline
**Parameters** & **Variable** & **Value** \\ \hline Frequency & \(Fr\) (GHz) & 2.45 \\ Transmitter power & \(P_{Tx}\) & \(-16\) \\ Transmitter antenna gain & \(G_{Tx}\) & \(-23.8\) \\ Receiver antenna gain & \(G_{Rx}\) & 3 \\ Distance & \(d(m)\) & 1–10 \\ Temperature & \(T_{0}(Kelvin)\) & 273 \\ Noise power density & \(N_{0}(dB/Hz)\) & 203.93 \\ Ideal-BPSK & \(E_{b}/N_{0}\) & 9.6 \\ Free space path loss & \(L_{f}(dB)\) & Distance dependent \\ Available power & \(A_{P}(dB)\) & Distance dependent \\ Required power & \(R_{P}(dB)\) & Adaptive (bitrate) \\ \hline \end{tabular}
\end{table}
Table 3: Link budget parameters of the proposed antenna.  
The iperf3 network performance testing tool was employed on a computer to measure the data transmission rates when the antenna was used as the receiver and the transmitter. The test results, as shown in Figure 18a, indicate that the data transmission rate is faster and more stable when the antenna is used as the receiver compared to when it is used as the transmitter. Additionally, it is evident that the distance between the transmitter and the receiver significantly affects data transmission. There is a noticeable decrease in transmission rate as the transmission distance increases. The fluctuations in transmission rate may be due to interference from other electronic devices and experimental instruments in the laboratory. The communication quality of the wireless communication module was also inspected using the iwconfig command, as shown in Figure 18b. The communication quality of the implantable antenna decreases with increasing communication distance. A slight improvement in communication quality is observed when the distance increases to 9 m, possibly because the antenna is placed on a table outside the laboratory at this distance. The relatively open space may be more conducive to data transmission. The experimental analysis indicates that the communication performance of the implantable antenna is affected by distance, with both communication rate and quality decreasing as distance increases.  
Since the actual application scenario for the implantable antenna is within human tissue, the distance between the antenna and external devices will not be too far. Therefore, despite the impact of distance on the antenna's communication performance, the distance over which the implantable antenna can maintain stable communication meets the actual needs of wireless telemetry.