Optimal Function-Based Frequency Offset Design Based on Polynomial Fitting for Frequency Diverse Array Beampattern Synthesis

In the letter, a new frequency offset generation method based on polynomial fitting is proposed. The frequency offset can be obtained by sampling the fitted curve. By adjusting the coefficients of the polynomial, different forms of frequency offset can be generated. Different from existing window-based frequency diverse arrays (FDAs), which adopt traditional window functions to generate frequency offset and suffer from high sidelobe levels (SLLs) and low range resolution, the performance of Poly-FDA can be more flexibly regulated by fitting different forms of polynomial curves. Moreover, the particle swarm optimization (PSO) algorithm is exploited in the coefficient optimization process to obtain the optimal polynomial curve and enhanced beampattern property. Numerical examples demonstrate the superiority and effectiveness of the proposed Poly-FDA with lower SLL and narrower beamwidth other than the existing window-based FDAs and FDA of other frequency offset forms.