Fast RCS computation over a frequency band using method of moments in conjunction with asymptotic waveform evaluation tech-Ž . nique, IEEE Trans Antennas Propagat 46 1998 . 4. D. Jiao, X.-Y. Zhu, and J.-M. Jin, Fast and accurate frequencysweep calculations using asymptotic waveform evaluation and the Ž . combined-field integral equation, Radio Sci 34 1999 , 1055᎐1063. 5. J.-P. Zhang and J.-M. Jin, Preliminary study of AWE method for FEM analysis of scattering problems, Microwave Opt Technol Ž . ABSTRACT: A discrete technique for phase unwrapping is presented. The technique is based on constructing the mth-degree interpolating polynomials to approximate the in¨ol¨ed functions using Legendre᎐ Gauss᎐Lobatto collocation nodes. The relationship between the known wrapped phase and the unknown unwrapped phase and that between their deri¨ati¨es are con¨erted into a set of linear algebraic equations. This set of equations is sol¨ed for the unknown coefficients to produce the unwrapped phase. A numerical example is included to demonstrate the performance of the technique, where a comparison is made with exact results.

An iterati¨e technique that uses sine and cosine modulations along with low-pass filtering to extract the true phase¨alues of a carrier frequency interferogram is proposed in this paper. An illustrati¨e example is gi¨en in which this technique is applied. Results generated from the application of this technique are compared with exact phasëalues, and excellent agreement between the exact and computed phasë alues is demonstrated. ᮊ

No abstract