Computation of the RCS of coated objects by a generalized PTD approach

Abstract

We consider the diffraction of an incident plane wave by 3D objects, such as missiles. These objects can be either perfectly conducting or coated with dielectric or magnetic coatings. Their shape, usually described in cad format, can be quite complex, with reentrant cavities, wings, ..., such that multiply reflected, reflected diffracted, and multiple diffracted rays exists. Morover, as these objects are designed to have a low rcs, these rays can be, for some angles of incidence, the main contributions to thercs. ptd is an efficient technique to compute thercs of complex objects, that has the desirable property of providing bounded results for any angle of incidence and observation. However, this theory has been mainly applied to perfectly conducting objects, the fringe wave is computed for wedge-like discontinuities, it does not include multiple phenomena. We have generalizedptd in three directions. First, we have extended the fringe wave concept to the case of an edge satisfying an impedance boundary condition. Second, we have computed diffraction by rounded edges or by tips by using an hybrid asymptotic-MoM method. Third, we have included multiply reflected or diffracted rays. We present some examples ofrcs and comparison with other methods.