Beamforming Optimization for Time-Modulated Circular-Aperture Grid Array With DE Algorithm

This letter put forward a method of numerical optimization for the circular-aperture time-modulated grid array. The amplitude weight and the time modulation pulsewidth are optimized based on a differential evolution algorithm to get the needed array pattern. Adopting the weighting mode of the conventional rectangular array, the equivalent weighting of a circular-aperture time-modulated array is decomposed into two independent components, respectively, in the horizontal and vertical directions, so as to shorten the length of the optimization vector from M x N order to M + N order. Besides, the circular-aperture time-modulated array is symmetrically excited in the horizontal and vertical directions. The numerical experiments show that the differential evolution algorithm can realize a sidelobe level of -35 dB and a nulling level of -60 dB in the patterns of the center frequency and one chosen sideband, and the unexploited sidebands are also suppressed with their peak levels lower than -35 dB. Meanwhile, the dynamic range of the amplitude weighting and the time modulation pulsewidth can be limited to 10 dB. The overall efficiency of the time-modulated array is 0.28.