shadow microwave holography
shadow scattered field component
inverse synthetic aperture radar
On the basis of available scientific publications the review of the results concerning a new development line in bistatic radiolocation - the inverse synthesizing of shadow microwave holograms of moving objects is done. Concepts and theoretical grounds of shadow inverse synthetic aperture radiolocation (SISAR) method with help of which there are possible the restoration of profile function of object shadow silhouette and its shadow spectral portrait, are analyzed. Materials of the review allow asserting, that the receiving of the synthesized shadow microwave holograms of the moving objects carrying the stable information on their shadow silhouette is inherent for bistatic radars based on the use of shadow component of the object’s forward scattered field. The list of publications on a theme of the review testifies to successful, approximately twenty years' period of development of the theory and practice of methods of bistatic forward scattering radiolocation and microwave holographic SISAR method.
The questions of calculation of objects shadow radar cross section and the signal-to-noise ratio in the shadow microwave hologram are considered. The mathematical models and the theory of the synthesized shadow microwave holograms, having good coincidence to experimental data are given. The complex profile function of the object connected with synthesized shadow microwave hologram by Fourier or Fresnel transforms is put into a basis of SISAR theory. At restoration of profile function the resolution of SISAR method can amount to the tenth or hundredth part of the object’s length. More convenient kind of a portrait in practice is the module of a spectrum of the complex shadow microwave hologram or the shadow spectral portrait having advantage before a profile portrait in view of it’s asymptotic invariance to some object trajectory parameters and simplicity of practical organization. For recognition of objects shadow spectral portraits the neural net algorithms application have the greatest efficiency. The results of neural net experiments testify to good coincidence to the reality of the SISAR method theory and also claim about an opportunity of further development of SISAR method.
Keywords: shadow microwave holography, bistatic radar, shadow scattered field component, inverse synthetic aperture radar.