RCS Calculation Research Articles

An extended UTD analysis for RCS computations involving higher order curved surfaces

The extended UTD (uniform geometrical theory of diffraction) analysis involves the use of spatial domain radiation integrals for the scattered fields. The relevant scattering mechanisms are then identified through uniform asymptotic evaluation procedures complemented with some rather heuristic modifications based on physical arguments. The typical scattering mechanisms involved are described by a new set of uniform reflection, first-order edge and zero-curvature diffraction coefficients that remain valid inside the transition regions and also reduce to the classic ray optical expressions in the exterior. In order to illustrate the accuracy of the extended UTD solution, numerical results are presented for a cubic polynomial strip and a superquadric cylinder. In both cases, the extended UTD result compares very well with the method of moments when the higher order mechanisms are not significant. The classic ray optical results, however, exhibit caustic singularities and discontinuities. >

Spectral iterative algorithm for RCS computation in electrically large or intermediate perfectly conducting cavities

A novel algorithm designed to compute efficiently and accurately the high-frequency electromagnetic scattering from open-ended waveguide cavities is presented. The cavity is converted into a stepped-waveguide model so that the field spectra are propagated, forward and backward, along each waveguide section. As boundary conditions for perfect electric conductors are applied via image theory, they are of local nature and take into account only the first-order interactions between each pair of waveguide sections. Accordingly, additional forward-backward iterations must be performed if multiple interactions are to be taken into account. Finally, the radar cross section due to the interior irradiation is calculated by a Kirchhoff-based aperture integral. Good agreement with method of moments and hybrid modal solutions is found, as well as with experimental data, for two-dimensional and three-dimensional cavities with rectangular cross section. >

Plane wave injection technique to calculate RCS in a 2-D TLM network

A technique for introducing an infinite-appearing plane wave into a two-dimensional transmission line matrix (TLM) network is described. The method has been applied to the calculation of the bistatic RCS for a plane wave normally incident on a conducting square cylinder.

RCS of electrically large targets modelled with NURBS surfaces

A technique is presented for the RCS computation of electrically large conducting bodies, modelled by NURBS patches, using physical optics (PO) and asymptotic expansion of integrals methods. The NURBS surfaces are transformed in Bezier patches to apply PO. Excellent accuracy is obtained.

A hybrid theory of diffraction for the RCS calculation of ogive‐like bodies

This hybrid theory of diffraction starts with the assumption that the dominant current on the scattering body is an optics type current close to 2 × . Near shadow boundaries on the body or discontinuities in the surface, the current may be represented by the moment method such that the total current in the vicinity of a shadow boundary or discontinuity is the sum of the optics current and the moment method current. (In this sense the method may be equivalent to the physical theory of diffraction.) The magnetic field integral equation is then used in an iterative procedure to obtain the correct current in the asymptotic regions (away from shadow boundaries) and in the moment method region. Because the iterative process starts with a current close to the true current, convergence is rapid with one or two iterations being typical. Results will be shown for ogives of various nose angles and diameters. The implication of these results on the further development of the (new) hybrid theory of diffraction will be discussed.

Correction to "Integral equation solution and RCS computation of a thin rectangular plate"

Correction to "Integral equation solution and RCS computation of a thin rectangular plate"