A Plane Wave Equivalent Model for Forward Scatter Shadow Ratio in Spherical Wave and Its Application in Shadow Profile Retrieval

Abstract

The forward scatter shadow ratio (FSSR), a novel parameter in forward scatter radar (FSR) systems, has been introduced recently for a plane wave. In contrast to conventional parameters like the forward scatter cross section (FSCS), FSSR utilizes the total electric field, providing a direct indicator of signal deviations from the direct path. This study overcomes the limitations of the current FSSR model by conducting a comprehensive mathematical and numerical analysis for a spherical wave with the Kirchhoff diffraction formula. By incorporating a point source and moving targets, this approach extends the application scope of FSSR. A plane wave equivalent model is derived and compared to the point source model, demonstrating its accuracy in various scenarios. The optimization method for target shadow profile retrieval in moving targets is discussed using the plane wave equivalent model. It is suggested that employing dual receivers can eliminate the ambiguity associated with target localization and enhance shadow profile retrieval precision.INDEX TERMS Forward scatter radar, forward scatter shadow ratio, shadow profile, diffraction I. INTRODUCTION

Pixel Based Shadow Profile Retrieval in Forward Scatter Radar Using Forward Scatter Shadow Ratio

“…1) is also established, with axes 𝑥′, 𝑦′ and 𝑧′ parallel with axes 𝑥, 𝑦 and 𝑧, respectively. As in [6,7], the target is considered moving straight in the 𝑧 1 Systems in a spherical wave can be converted to plane wave equivalent systems [6]. direction on the 𝑥-z plane, i.e., the origin of the 𝑥 − 𝑦 − 𝑧′ system is moving straight in the 𝑧 direction on the 𝑥 − 𝑧 plane.…”

“…It can be seen that the additional receiver can improve the accuracy of the shadow profile retrieval. For comparison, the retrieval results using the strip based method [6,11] for the same two fleet formations are shown in Figs. 14(c) and (d), respectively.…”

“…Forward scatter shadow ratio (FSSR), defined as the ratio of the total received power density to the direct path signal (DPS) power density, is a parameter to describe the target in an FSR system [6][7][8]. Compared with forward scatter cross section (FSCS) [9,10], it has been shown that FSSR is more relevant to passive FSR systems [6][7][8]. Based on FSSR, an optimization method for target shadow profile retrieval has been recently proposed [7,8,11,12].…”