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A Novel Anti-Stealth Technique Based on Stratospheric Balloon-Borne Radar in Heterogeneous Environments

Abstract Radar cross section (RCS) of a stealth target model like F-117A can be improved by multichannel stratospheric balloon-borne bistatic radar at higher aspect angle. The potential problem is that the stealth target may produce range walk in clutter heterogeneous environments, thus it is difficult to determine the range ambiguity under quadratic range cell migration (QRCM). In this paper, a novel detection technique known as hybrid modified fractional-radon Fourier transform (MFrRFT) and knowledge-aided space–time adaptive processes (KA-STAP) is proposed to impact this kind of problem simultaneously. KA-STAP is applied to suppress the non-homogeneous clutter in the received data, and MFrRFT is used to eliminate the QRCM along with the second-order keystone transform (SOKT), so as to estimate the range ambiguity and compensate the stealth target’s range walk. The hybrid MFrRFT/KA-STAP scheme is simple and applicable to the small RCS of fast stealth target with a long-time coherent integration. Finally, to achieve high accuracy of locating stealth target, a non-parametric detection technique based on Legendre orthogonal polynomials is applied to reconstruct the probability density function (pdf) of real RCS data predicted by physical optics (PO) approximation method.