Direct scattering methods in presence of interfaces with different media

Several techniques have been developed to solve the direct scattering problem from targets involving different media and interfaces. For the case of stratified media and embedded targets, different formulations based on integral equations solved with method of moments have been proposed. Time-domain methods have the advantage to return results in the form of radargrams typical of measurements with pulsed techniques. Among them, the Finite-Difference Time-Domain method is widely used due to its high flexibility in the simulation of targets and backgrounds of arbitrary shape. For the case of targets with canonical shape, i.e., circular cross-section cylinders, in a non-homogeneous background, the Cylindrical Wave Approach gives a semi-analytical solution that is fast and accurate.