Synthesis of Large Ultrawideband Sparse Planar Arrays by Utilizing a Cooperative Coevolutionary Iterative Fourier Transform

This letter introduces a cooperative coevolutionary iterative Fourier transform (CCIFT) technique to extend the conventional iterative Fourier transform (IFT) to large ultrawideband (UWB) sparse planar array synthesis. In the proposed CCIFT, a dense initial element position grid, such as a spacing of half a wavelength at the highest frequency, is adopted to avoid the presence of grating lobes at high frequency band, and a probability-assisted element selection mechanism is presented to guarantee the obtained array layout to meet a preset minimum spacing constraint, enabling the placement of physical UWB antenna elements. In addition, a cooperative coevolutionary strategy is presented to avoid prematurity by establishing the information interaction between different excitation distributions from multiple parallel IFT procedures. Two examples are conducted and results show that the CCIFT can achieve a considerably lower peak sidelobe level than some state-of-the-art algorithms within an acceptable CPU time, which demonstrates its effectiveness and superiority.