Analysis on Bistatic Target Strength of Benchmark Submarine Based on Improved Planar Element Method

Bistatic target strength is an important parameter of bistatic or multistatic sonar. This paper uses an improved bistatic planar element method to analyze benchmark submarine. Firstly, by applying the improved monostatic planar element method to bistatic case, an improved bistatic planar element method is derived and then compared with analytic method. Secondly, the target strength of the benchmark submarine containing external hull, internal hull and rib plates is analyzed considering secondary scattering and occlusion. Thirdly, the statistical characteristics of the bistatic target strength are analyzed. The results indicate that: 1) the improved bistatic planar element method has high accuracy when the bistatic angle is not very large, and it can avoid huge amount of calculation due to coordinate conversion and improve computational stability; 2) for the double-hull benchmark submarine, the primary scattering of the external hull contributes mainly to the target strength in most cases, while the secondary scattering of the external hull is much weaker, and when the incident and scattering directions are symmetrical about the stern or stem direction, the scattering of the internal hull and rib plates contributes a lot due to the mirror reflection; and 3) the statistical characteristics of the bistatic target strength vary slightly with the bistatic angle. This work may provide a reference for the design of bistatic or multistatic sonar for undersea weapons.