An efficient procedure to analyze locally-modified scattering problems by using the characteristic basis function method

In recent years, the advent of fast digital computers has facilitated the use of numerical methods for the solution of large scattering problems. The Method of Moment (MoM) has been widely used to solve integral equations in the frequency-domain. Its application entails approximating the unknown current distribution on the scatterer and transforming the integral equation into a set of linear algebraic that is generally solved by using direct or iterative methods. For electrically large scattering problems, the number of unknowns can reach several millions; hence the use of a direct solver, such as LU decomposition, becomes impracticable because of heavy burden it imposes on the CPU.