IMPROVEMENT OF THE RAYLEIGH APPROXIMATION FOR SCATTERING FROM A SMALLSCATTERER

An improvement of the Rayleigh approximation for electromagnetic scatt ering from an arbitrary small scatterer is developed through solving t he conventional integro-differential equation governing the electric f ield inside the scatterer. The improvement is represented by an equiva lent polarizability tenser differing from that used in the Rayleigh ap proximation in two aspects: i) it is frequency dependent, and ii) it g ives a scattering amplitude tenser satisfying energy conservation. The energy conservation is investigated through formulating the extinctio n, scattering, and absorption losses according to the equivalent polar izability tenser. Numerical calculations on spheres and spheroids indi cate that the present extinction loss formulation has a wider validity range than the extinction loss formulation according to the Rayleigh approximation.