In mathematics and physics, the inverse scattering problem is the problem of determining characteristics of an object, based on data of how it scatters incoming radiation or particles. It is the inverse problem to the direct scattering problem, which is to determine how radiation or particles are scattered based on the properties of the scatterer. The study of the inverse scattering source problem in the frequency domain focuses on nding the source f from the prescribed boundary condition, which is generally given as Cauchy data containing both the solution on the boundary and its normal derivative. The result of this research has direct application to antenna synthesis, biomedical and medical imaging and seismology