# Analysis of High-Power Radar Propagation Environments Around the Test Site
## 1 Introduction  
In military applications, the importance of radar systems capable of accurately detecting and tracking enemy attacks in advance is growing [1, 2, 3, 4]. During the operation of these radar systems, the occurrence of false positives or false negatives can result in unnecessary responses [5, 6, 7]. Consequently, ensuring reliability and accuracy is crucial for the stable operation of the radar system. For this reason, radar performance testing is considered an essential procedure, which is conducted at test sites similar to actual operating environments [8, 9]. This performance test is carried out by steering the Tx. radar toward Rx. probe antenna. In this process, a high power of electromagnetic (EM) waves is emitted not only through the radar's main lobe but also through the side lobes [10]. These EM waves may be transmitted to areas other than the receiver due to the reflection, diffraction, and scattering caused by the complexity of surrounding structures such as trees and buildings [11, 12, 13]. In particular, the reference level for electric field strength is established at 61 V/m whenthe EM waves are transmitted to areas accessible to the general public [14]. Thus, a precise analysis of the propagation environment, including both direct and indirect paths, as well as the electric field strength around the test areas, is required before radar performance testing. To predict such a propagation environment, empirical statistical models such as the Okumura and Hata models, as well as ITU-R models (P.452-17, P.530-18, P.1546-6), which can be applied to various frequencies, have been utilized [15; 16; 17; 18]. However, these models are limited in accuracy because they depend on statistical methods and do not accurately account for structures such as terrain and buildings. Although studies have been conducted in specific regions using precise modeling and simulation (M&S), these have primarily focused on analyzing direct and indirect paths [19; 20]. Therefore, comprehensive research is needed to evaluate the impact of environmental factors, including terrain and buildings, on the radio environment surrounding radar test sites.  
In this paper, we propose a novel evaluation method for the strength of EM waves in the area by analyzing the propagation environment in a radar testing site. This evaluation method, which utilizes EM simulation, follows three steps: First, to analyze the propagation environment of the radar test site, actual structures, such as buildings and terrain, are precisely modeled. An integrated model is then set up by applying them to a propagation simulation tool (Wireless InSite 3.3.0 software). Herein, the terrain is modeled using digital elevation model (DEM) data provided by the Ministry of Land, Infrastructure, and Transport. Second, the EM waves transmitted from the Tx. system to Rx. system are classified into the direct path and the indirect path. The received power around each system is analyzed based on the sum of these paths. Third, we convert the calculated received power into electric field strength for comparison with a reference threshold level. Through this process, we analyze two scenarios: one is when the Tx. is directed toward the Rx., and the other is when the radar is misaligned. Finally, in the misaligned scenario, we evaluate the electric field strength by placing absorbers on the Tx. radar building. To verify the accuracy of the proposed evaluation method, we conduct measurements at an actual radar site and compare the measured received power with the simulation results.