# Analysis of the Dihedral Corner Reflector's RCS Features in Multi-Resource SAR
## 1 Introduction  
The artificial corner reflector (CR) has been effectively applied in SAR calibration and deformation monitoring of Synthetic Aperture Radar (SAR) images for decades [1; 2; 3; 4]. Owing to their exceptional scattering properties and precise coordinates, CRs play a crucial role in accurately determining SAR antenna patterns and absolute radiation calibration constants [1; 5]. Additionally, they serve as precise control points for detecting geometric offsets in SAR images caused by satellite orbit deviations, geodynamic signals and so on [3; 6; 7]. CRs provide indispensable support for SAR sensor geometric and radiometric calibration, as well as the quality analysis of SAR images. In 2007, [PERSON] et al. demonstrated the millimeter-level precision achievable in deformation monitoring using artificial permanent scatterers through a mobile dihedral CR and Permanent Scatterer Interferometric SAR (PSInSAR) [8]. [PERSON] et al. [9] and [PERSON] et al. [10] identified millimeter-level deformation trends in highway areas and landslides, respectively, by employing CRs. [PERSON] et al. [11] and [PERSON] et al. [12] employed CR offset-tracking technology within mining areas and glacier monitoring, respectively. In both studies, significant meter-level deformation information was successfully extracted. Moreover, CRs have been applied in studies related to absolute positioning [13; 14] and scatterer localization [15; 16] in SAR images, showing significant potential for various applications. The analysis of the Radar Cross Section (RCS) of CRs holds significant importance in SAR calibration, CR design and the assessment of monitoring accuracy [17]. The triangular CR is widely employed due to its stable structure and large angle of 3 dB RCS reductionin the azimuth direction. Extensive theoretical analysis and experimental research on the RCS of triangular CRs have been conducted [18; 19; 20; 21]. [PERSON] et al. [20] deployed over 40 triangular CRs in Gunning, Australia, and studied the factors contributing to RCS loss of triangular CRs under multi-resource SAR data. They also provided size selection and installation recommendations for triangular CRs under different bands. In comparison to the triangular CR, the dihedral CR is characterized by a simpler structure and stronger scattering signal under the same size. However, due to the high sensitivity in azimuthal alignment deviations, there has been limited research on RCS measurements and deformation monitoring applications related to the dihedral CR. Currently, the RCS analysis of dihedral CRs is primarily focused on theoretical simulation. [PERSON] et al. [22] and [PERSON] et al. [23], based on physical optics and diffraction theory, have derived a model for the RCS reduction of dihedral CRs at any viewing angle. [PERSON] et al. 's study indicates that a \(5^{\circ}\) vertical angle discrepancy between two panels results in approximately 6 dB RCS reduction [24]. [PERSON] et al. [25] and [PERSON] et al. [26] analyzed the impact of a dielectric constant and the coating of absorptive materials to the RCS of dihedral CRs. The result indicates that a normalized surface impedance coefficient of 0.2 leads to an approximate 5 dBsm loss in scattered energy. The theoretical RCS formulas in previous studies take into account the incident angles, the included angle between the two panels and the dielectric constant. However, it was excessively complicated when these formulas were applied to the panel dimension and tilt angle design of dihedral CRs for SAR deformation monitoring applications. Due to the novel design of the dihedral CR in this paper and numerous commercial SAR satellites with different incident angles, the CR's axis will misalign with the SAR incident signal, resulting in RCS reduction and deformation monitoring accuracy discrepancy. Furthermore, testing the dihedral CR's performance in real SAR data is essential for the CR design in the landslide monitoring project.