## 4 Results  
This section details the outcomes derived from simulating the proposed photonic radar system. This system is founded on FMCW technology and incorporates MIMO-IIR for the detection and ranging of various targets, utilizing the MDM scheme. For the purposes of this study, two independent targets were positioned at distances of 75 m and 55 m from the photonic radar. The system's configuration was designed with a bandwidth of 4 GHz, which is substantial for high-resolution target detection. The initial evaluation of the proposed system was conducted under optimal atmospheric conditions, where the weather was clear, and the targets were stationary. This setting provided a controlled environment to assess the system's basic detection capabilities. The assumed atmospheric attenuation was relatively low at 0.2 dB/km, minimizing the impact on the signal's strength over a large distance, which is essential for accurate target detection. The range frequency \(f_{r}\) at which the echo signal occurs can be calculated using the fundamental principles of FMCW radar systems. The equation for \(f_{r}\) typically takes into account the rate of change of frequency with respect to time given that the frequency of the transmitted signal increases linearly with time during the sweep. The formula to calculate the range frequency \(f_{r}\) is given by [22]:  
\[f_{r}=\frac{(2\times R\times B)}{(T_{m}\times c)} \tag{7}\]  
where \(B\) is the bandwidth, \(R\) is the range or the distance of the target, \(T_{m}\) is the sweep time, and \(c\) is the speed of light. Figure 3 presents the results of this detection scenario, illustrating the system's ability to identify multiple targets in such clear conditions. As illustrated in Figure 3, the proposed photonic radar system successfully detects two targets in clear weather conditions. The range frequency calculated using Equation (7) is 200 MHz for target 1 and 146.30 MHz for target 2, which matches the detected range frequency, as shown in Figure 3. This confirms the accuracy of the proposed system. Figure 3a displays the detection results without the utilization of the IIR technique, indicating maximum received power levels of \(-13\) dBm for target 1 and \(-9\) dBm for target 2. In contrast, Figure 3b exhibits the detection outcomes with the implementation of the IIR technique, showing significant power improvements with maximum received power levels of 13 dBm for target 1 and 14 dBm for target 2. The power improvement achieved using the IIR filter is calculated mathematically using Equation (7) as follows:  
\[\rm{Power\ improvement}\ (\%age)\ =\frac{P_{out\_with\_IIR}-P_{out\_without\_IIR}}{P_{ out\_without\_IIR}}\times 100 \tag{8}\]According to the equation above, the percentage of power improvement is 200% for target 1 and 276.73% for target 2. These results demonstrate the significant impact of the IIR technique in increasing the detection capability of the proposed photonic radar system. The performance of the proposed photonic radar is further tested for the impact of varying weather conditions. Figure 4 depicts the impact of different attenuation levels on the proposed photonic radar system. As illustrated in Figure 4, the proposed photonic radar system successfully detects two targets in attenuated weather conditions. Once more, the mathematically calculated range frequency matches the detected range frequency under heavy attenuation, as shown in Figure 4.  
This confirms the accuracy of the detection of the proposed system even under heavy attenuation of 75 dB. Figure 4a displays the detection results without the utilization of the IIR technique for targets, and Figure 4b shows the detection of targets with IIR. The power improvement achieved using the IIR filter is visible in Figure 4b. It can be inferred that the utilization of the IIR technique in a photonic radar system can result in a reduction in the input power requirements. This, in turn, will lead to a decrease in power consumption, ultimately prolonging the lifespan of the autonomous vehicle's battery.