Sidelobe Level and Aperture Efficiency Optimization for Tiled Aperiodic Array Antennas

Abstract

Array antennas with aperiodic element placement provide a way to mitigate grating lobe level when the array element spacing is larger than one half wavelength. Design techniques for aperiodic arrays include thinning, numerical optimization, and other methods, but even with modern tools, designing electrically large aperiodic arrays remain computationally challenging. To reduce the complexity of the large aperiodic array design problem, we study the use of discrete rotated tiles with element positions and tile orientations optimized to minimize peak sidelobe level (PSLL). The directivity, frequency sensitivity of PSLL, and optimization complexity for uniform arrays, aperiodic arrays, and tiled arrays are compared. Based on many numerical examples, an approximate relationship between PSLL and array element number and density for aperiodic and tiled arrays is proposed as a convergence estimator for the design optimization process.