# X-Band Photonic-Based Pulsed Radar Architecture with a High Range Resolution
## 3 Experimental Setup and Results
As can be confirmed in Figure 7b, when the two targets were located at the same distance from the antenna, it is 3 m distance from two targets to the antenna. According to Fraunhofer's distance, the minimum distance, which satisfied the far-field condition, from the antenna to the target is 2.6 m. The calculated Fraunhofer distance of the system is closer than the distance when two targets are located at the same range from the antenna, therefore, it can be assumed that two targets exist in far-field. In far-field conditions, through Equation (12), the cross-range resolution can be obtained as 0.68 m, which is quite inferior compared with the range resolution because of the wide beamwidth of the antenna. Consequently, because the separation of the two targets is more affected by the range resolution than the cross-range resolution considering the antenna beamwidth used in this experiment, the two targets can be recognized separately due to the difference in the distance produced as the targets movement. In order to compare the characteristics of the proposed photonic-based pulsed radar architecture with the results of the previous studies, Table 1 summarizes the main characteristics of the previously studied photonic-based radar. As can be seen from Table 1, it can be seen that the proposed pulsed radar architecture has the significantly broad bandwidth of the transmitted signal than the signal bandwidth of the previous photonic-based radar with MLL research results. The bandwidth of the experimental result is less than 1 GHz, which is narrower than that of the previously studied CW laser-based research result, but this result is due to the narrow bandwidth of the IF signal generated by the AWG. If the bandwidth of the IF signal becomes several GHz as in the previous study, it is also possible to generate a wideband signal similar to the previous study result in the photonic-based pulsed radar structure proposed in this paper. In addition, maximum detectable range in Table 1 is definitely depends on the RCS of the target and the transmit power. Due to the limitations of the indoor test circumstance, the indoor experiments were conducted within several meters by adding attenuators to reduce the transmit power. If eliminate the use of attenuators and replace the high power amplifier at the transmitter with Qorvo Inc.: Greensboro, NC, USA, TGA2704-SM model, the maximum detectable range can be obtained as shown in Table 1. In Table 1, maximum range refers to the distance used in the experiment if the maximum detectable range is not disclosed in the papers. If the maximum detectable range is not disclosed among the previous research results compared in Table 1, the maximum range can be inferred through information such as an RCS of the used target, the transmit power, and total system loss of the radar system. However, if there is not disclosed information about the radar system, the detectable range must be inferred through the types of radar. In general, the maximum detectable range of an FMCW radar is relatively small than the maximum range of a pulsed radar [13]. In this paper, the maximum detectable range was calculated by assuming that RCS is 1 m\({}^{2}\) 0 dBm) and the maximum range can be increased if the RCS of the target is assumed more than 1 m\({}^{2}\).