Fast Low-Sidelobe Pattern Synthesis for Linear Array Thinning Utilizing a Modified Iterative Chirp-Z Transform Technique

Abstract

A novel algorithm is presented for the pattern synthesis of thinning uniformly spaced linear arrays generating a lower peak sidelobe level. The novel algorithm is based on a modified iterative Chirp-Z transform (MICZT) technique integrated with an adaptively changing fill factor mechanism. The iterative Fourier transform (IFT) method has to be performed a large number of independent trials to find the optimum turned “ON” element distribution, but often easily gets trapped in local optima. The MICZT technique is proposed to accelerate the synthesis efficiency and facilitate global convergence. In the proposed technique, the ability to approach the global optimal is embodied in two aspects. On the one hand, array thinning is accomplished by setting the possible element state of “ON” and “OFF” according to the adaptively changing fill factor during each iteration cycle. On the other hand, the initial element distribution during each independent trial is almost a full array. So the thinned array distributions obtained after several iterations can still inherit some excellent characteristics of the full array. Several representative examples of linear array thinning are given to demonstrate the superiority, effectiveness and good robustness of the MICZT technique.