A hybrid technique for analysis of scattering from circular cavities with cylindrically periodic terminations

The cavity problem formulated via a magnetic field integral equation (MFIE) has been solved by the iterative physical optics method (IPO) and the progressive physical optics (PPO) method. In this paper, an alternative hybrid technique is presented to efficiently solve the MFIE. The focus is on open-ended circular cavities with cylindrically periodic terminations. The computational size can be significantly reduced by exploiting the periodicity of the terminations. The boundary element method (BEM) is used to represent the original geometry. And the discrete Fourier transform technique (DFTT) is applied to reduce the original computational size by a factor N/sub s/, where N/sub s/ denotes the number of blades in the cylindrically periodic termination. A 3-D circulant wavelet basis transform is effectively implemented with the DFTT, making the impedance matrices very sparse in the wavelet domain which can be solved efficiently by sparse solvers. Numerical results are presented to demonstrate the merits of the proposed method.