Abstract:This paper proposes a novel mixed genetic algorithm——Active Mutating Anneal-Genetic Algorithm(AMAGA) based on sorting and describes an elevation beam widening method of spaceborne SAR antenna, which only changes the phases at part of array elements and so called Partly Phase-only Weighting Method (PPWM). Moreover, the resulting phases need not be quantized and can be directly applied to engineering project. In comparison with the fully phase-only weighting method for beam widening, the partly phase-only method for beam widening is more realizable and more flexible. Simulated examples show that the mainlobe notch of widened beam can be controlled finely with lower sidelobe.