## 2 Materials and Methods
### DVB-S Passive FSR Experimental Campaign for Drone Detection  
The experiment was conducted in an open area (futsal court), at the Faculty of Engineering, University Putra Malaysia (UPM). A geostationary earth orbit (GEO), DVB-S satellite located at 91.5E, 35,921 km above the sea level was used as the illuminator of opportunity and served as the transmitter. Figure 4 illustrates the aerial view of the experimental site. The FSR topology enables the receiver to \begin{table}
\begin{tabular}{c c c} \hline \hline
**Material Type** & **Plastic** & **PEC** \\ \hline \multicolumn{3}{c}{**Blade face facing E-field direction**} \\ \hline Main lobe magnitude (dBm\({}^{2}\)) & \(-\)49.7 & 0.877 \\ Main lobe direction & 183\({}^{\circ}\) & 180\({}^{\circ}\) \\ Angular width (3 dB) & 71.9\({}^{\circ}\) & 44.6\({}^{\circ}\) \\ Side lobe level (dB) & \(-\)10.7 & \(-\)5.8 \\ \hline \multicolumn{3}{c}{**Blade edge facing E-field direction**} \\ \hline Main lobe magnitude (dBm\({}^{2}\)) & \(-\)56.5 & \(-\)13.6 \\ Main lobe direction & 6.0\({}^{\circ}\) & 112.0\({}^{\circ}\) \\ Angular width (3 dB) & 113.6\({}^{\circ}\) & 41.2\({}^{\circ}\) \\ Side lobe level (dB) & \(-\)7.0 & \(-\)1.2 \\ \hline \multicolumn{3}{c}{**Blade tip facing E-field direction**} \\ \hline Main lobe magnitude (dBm\({}^{2}\)) & \(-\)59.7 & \(-\)16.3 \\ Main lobe direction & 217.0\({}^{\circ}\) & 179.0\({}^{\circ}\) \\ Angular width (3 dB) & 11.4\({}^{\circ}\) & 23.7\({}^{\circ}\) \\ Side lobe level (dB) & \(-\)2.8 & \(-\)2.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Cartesian and Polar summary of values for plastic and PEC materials. Figure 3: Drone blade’s RCS in Cartesian and Polar coordinates at three different blade orientations for (**a**) PEC and (**b**) Plastic. receive a signal component of both scattered and the direct signal from the transmitter (signal source), and maintained the general bistatic Doppler frequency equation, as shown in (1) [36]  
\[f_{d}\ =\ \frac{2v}{\lambda}cos(\frac{\beta}{2})cos(\delta) \tag{1}\]  
where \(v\) = moving target velocity, \([cos(\frac{\beta}{2})cos(\delta)]\) is the coefficient factors due to bistatic geometry, \(\delta\) is the angle between the velocity direction FS baseline, and \(\lambda\) is the wavelength. For simplicity, the baseline formation between the satellite and the receiver is assumed to have their main lobe be in the same direction. The FSR receiver circuit is considered simple and comprises of a customized low noise block (LNB) installed attached to the dish antenna. The feed horn is located at the dish's focal point to receive the focused reflected energy by the dish. The down conversion process begins from the output of the waveguide probe passing through a Ku-band pass filter to remove the unwanted frequencies. Due to the low power signal received, an LNA was made to amplify the signal power to meet the sensitivity level of the amplitude detector and then passes through a low-pass filter. The LPF output is converted to digital form by an analogue to digital converter (ADC) and saved for signal processing. The block diagram of the DVB-S p-FSR receiver is illustrated in Figure 5.  
Figure 4: Aerial view of the experimental site, the ground station located in a futsal court with a clear canopy. Figure 5: FSR receiver block diagram to receive direct DVB-S signal and signal scattered by the drone. The signal under consideration had an approximate calculated power received of \(-\)110 dBm. This signal power was considered low, but sufficient to be utilized by the FSR system; nevertheless, the system further amplified the signal before the non-linear device process. An LNA with a 20-dB gain and a noise figure of 2 dB, with an output capability of up to +25 dBm, was used within Ku-band frequencies. The LNA improved the signal power to the required level for a successful down-conversion process and ensured that the signal power was higher than the diode sensitivity level. The complete passive FSR system was set up to capture the Measat3 signal waveform.