Optimization of Far-Field Patterns Based on Direct Synthesis Results

Electromagnetic radiation patterns can be directly synthesized using the propagation modes corresponding to a linear source or a rectangular current sheet. This communication shows that, although the directly synthesized patterns usually have high sidelobe levels and large ripples in the main beams, they can be used as very good initial patterns for further optimization. By tracing the extrema of the radiation pattern flexibly, the sidelobe levels and the ripples in the main beams can be effectively controlled. Since the number of the extrema is approximately equal to the number of degrees of freedom of the far field, the algorithm converges monotonically. Numerical examples validate the hybrid optimization algorithm.