Application of adaptive algorithms for near-field far-field transformation

A new approach is introduced for formulating the near-field to far-field transformation of the scattered field. The scattered field is expanded as a series of summation in terms of modal wave functions. For the transformation of the scattered field the expansion coefficients should be determined. We applied the adaptive solution algorithms for extracting unknown expansion coefficients, because of the application simplicity, noise exemption and computational efficiency. These unknown coefficients can be found by the minimization of the adaptive algorithm error using the limited number of measurement points around the object. Then, the scattered fields at the desired points can be calculated by using these determined coefficients. We choose the least mean square adaptation (LMS) algorithm and apply it to the scattered fields of different objects for noisy and noise free cases. We discovered that the adaptive algorithm transforms the scattered field with a greater accuracy and lower computation time than the harmonic expansion technique