Research On The Measurement Of Reflection Coefficients At Oblique Incidence For Stealth Material Used On Underwater Weapons

The development and application of stealth techniques have improved significantly the survivability and the penetration capability of weaponry, and given an inestimable impetus to modern warfare. Covering the surface of submarines with stealth material is one of the most important methods for acoustical stealth. With the breakthrough of new stealth mechanism and the application of new stealth material, the stealth weapons are attached increasing importance to every country, and the research of measuring method and measuring system is also accelerated.The reconstruction of reflection coefficients using active Near-field Acoustical Holography is based on the theory of wave acoustics. The method involves the measurement of complex pressure distribution on two parallel planes lying between the surface of a test material and the source, and decomposing each of the complex pressure distributions into plane-wave components by using 2-D spatial Fourier transform. Then, the reflection coefficients at arbitrary oblique incidence could be reconstructed.The principle of this method is described in this paper, and two measuring models are provided based on NAH. One of them is constructed in full-space and the other in Semi-space. Systematical simulation is carried out, which result shows the influences of various factors on the reconstruction. A measuring system is set up based on the simulation. The reflection coefficients of a rectangular steel plane have been measured by using the measuring system. The experiment results have a good accordance with the theoretical values. Based on the above research work, the reflection coefficient of a kind of stealth material has also been analyzed by experiment.