A hybrid diffraction technique--General theory and applications

A new method is presented for calculating the current on a perfectly conducting body. The starting point of the method is in the assumption that the dominant current on the scattering body is an optics type current close to
2\hat{n} \times \bar{H}^{i}
. Near shadow boundaries, the current is represented by the moment method such that the total current in the vicinity of a shadow boundary is the sum of the optics current and the moment method current. (In this sense the method may be equivalent to the physical theory of diffraction.) The magnetic field integral equation is then used in an iterative procedure to obtain the correct current in the asymptotic regions (away from shadow boundaries) and in the moment method region. Because the iterative process starts with a current close to the true current, convergence is rapid with two or three iterations being typical. The general theory is presented and then applied to the infinite wedge problem and to the problem of a two-dimensional square cylinder. Results are compared with other independent solutions, and excellent agreement is demonstrated. A comparison is made with conventional physical optics. Application of the hybrid diffraction method to curved surfaces is discussed. Advantages and disadvantages of the method are also discussed.