Design of Sum and Difference Patterns by Optimizing Element Rotations and Positions for Linear Dipole Array

This communication presents a novel method of synthesizing both sum and difference patterns by optimizing the element rotations and positions for linear dipole array. The common element rotations and positions are optimized by using the particle swarm optimization (PSO) method to produce sum and difference patterns with reduced sidelobe levels (SLLs) and cross-polarization levels (XPLs) and as steep slope as possible for the difference pattern at the target direction. Such a method leads to a sum-and-difference array with sparsely distributed uniform amplitude elements, thus saving many antenna elements and unequal power dividers. Three examples for synthesizing sparse rotated dipole arrays with sum and difference patterns are provided. Synthesis results show that the obtained arrays with uniform amplitudes can produce the satisfactory sum and difference patterns while saving about 34.69% ~ 42.27% of the antenna elements compared with λ/2-spaced arrays occupying the same aperture.