Zero-backscatter cloak for aspherical particles using a generalized DDA formalism

The Discrete Dipole Approximation (DDA) formalism has been generalized to materials with permeabilities mu; not equal 1 to study the scattering properties of impedance-matched aspherical particles and cloaked spheres. We have shown analytically that any impedance-matched particle with a four-fold rotational symmetry with respect to the direction of the incident radiation has the feature of zero backscatter. Moreover, an impedance-matched coat with the aforementioned symmetry property acting on an irregular dielectric particle with the same symmetry property can substantially reduce the backscatter. This leads to a substantial reduction of the signals from an object being detected by a monostatic radar/lidar system. The DDA simulation also provides accurate information about electric field distributions in the vicinity of a cloaked sphere.