# Analysis of High-Power Radar Propagation Environments Around the Test Site
## 3 Analysis of the Propagation Environment During Radar Operation  
Figure 3 illustrates the radiation patterns of the radar system used in the simulation. In our study, we analyze the X-band and Ku-band frequencies based on actual radar specifications. The beam pattern for the patch array antenna is generated using the antenna design software CST Studio Suite 2020 EM simulator [26] and then converted into a format compatible with Wireless InSite. The radiation patterns of the radar system are generated using a uniform planar array of single patch antennas, based on the standard array factor approach. In Figure 3a, the red solid line indicates the radiation pattern for the X-band, while the blue line presents the radiation pattern for the Ku-band. The generated X-band radar radiation pattern has a bore-sight gain of 30.07 dBi, a 3 dB beamwidth of 4.9\({}^{\circ}\), and a sidelobe level of 13.3 dB. The Ku-band radiation pattern has a bore-sight gain of 35.86 dBi, a 3 dB beamwidth of 2.2\({}^{\circ}\), and a sidelobe level of 13.5 dB. The characteristics of the X-band and Ku-band radar systems are listed in Table 1. Figure 3b shows 3D radiation pattern of test radar in simulation model. In the simulation, the radiation pattern of the test radar is positioned 5 m above the top of the radar control center, and the frequency-specific radiation patterns shown in Figure 3a are applied according to each simulation case. Figure 3: Radiation patterns of the radar system for Wireless Insite simulation: (**a**) radiation patterns of the test radar; (**b**) 3D radiation pattern at 18 GHz in the simulation model. Figure 2: Simulation model for the analysis of EM wave propagation environment. Figure 4 illustrates the analysis of the propagation environment in a radar testing scenario using the proposed simulation model. To analyze the EM waves transmitted around the Tx. system and Rx. system through both direct and indirect paths, the observation points are placed at 2 m intervals in the radar site. Herein, the direct path refers to the line-of-sight (LoS) between the Tx. and Rx. of the radar system, while the indirect path consists of waves that are reflected, diffracted, or scattered by terrain and buildings. A \(\lambda\)/4 monopole antenna (5.15 dBi) is placed at the top of the beacon tower (60 m above the ground) to examine the propagation path to the Rx. System. Figure 4a shows not only the direct path (red solid line) but also the indirect path (yellow solid line), which is caused by the side lobe of the radar and reflection by the terrain. Although the radar is directed towards the Rx. system, the results indicate that the transmitted EM waves reach the surrounding terrain and are received through various paths due to reflection and diffraction. Figure 4b provides the received power distribution around the Tx. radar and the Rx. system in the X-band. The transmitted power of the radar is set at 1 W (30 dBm), and the received power at each location is listed in Table 2. According to the results of the X-band, the maximum received power of \(-\)44.39 dBm and \(-\)52.86 dBm in the surrounding areas of the Tx. and Rx. systems are calculated, respectively. These results can be converted to electric field strengths of 0.19 V/m and 0.07 V/m, which are significantly lower than the reference level of 61 V/m. Figure 4c represents an analysis for the Ku-Band, and the maximum received power of \(-\)59.09 dBm (0.08 V/m) and \(-\)59.94 dBm (0.07 V/m) is calculated and confirmed to be lower than the reference level. Figure 5 illustrates the distribution of received power in the X-band and Ku-band with steering toward a nearby area. The transmitted power is set to 1 W, and the elevation angle of the radar is adjusted to \(-\)30\({}^{\circ}\), which allows the signal to reach the nearby area in the shortest distance. The transmitted power is attenuated by a path loss of 88.2 dB and 96.6 dB in the X-band and Ku-band, respectively, over 76.7 m until reaching the ground.