T-MATRIX IMPLEMENTATION OF FORWARD SCATTERING FROM RIGID STRUCTURES

The T-matrix method is applied to compute forward scattering from rigi d structures. The method requires evaluation of matrix elements Q(lk)m m whose imaginary parts with l<k are difficult to evaluate for long, s lender, nonellipsoidal structures because the evaluation involves inte grations of large oscillatory functions. A new approach for the evalua tion of these elements is shown for finite cylinders where the antisym metric part of the matrix is written in a form involving integrals tha t are easier to compute. Forward scattering results are shown for sphe roids and cylinders with spheroidal endcaps where the length of the cy lindrical section is shown to have little effect on forward scattering . The magnitude of the forward scattering at the high-frequency limit is seen to be proportional to the cross-sectional area, which is in ag reement with the high-frequency Kirchhoff approximation.