Nature-Inspired Design Techniques for Ultra-Wideband Aperiodic Antenna Arrays

Over the past few decades, much research has been invested in the exploration of wideband and ultra-wideband (UWB) antenna arrays. The goals of such array designs are to determine the best element arrangements, which yield radiation patterns possessing the highest degrees of side lobe suppression, and no grating lobes over the largest possible operating bandwidths. It has been recently shown that nature-inspired array-design methodologies can provide solutions that exhibit these ultra-wideband characteristics. This article provides an overview of two such designs:linear polyfractal arrays, and planar arrays of aperiodic tilings. Robust nature-inspired genetic-algorithm optimization techniques were utilized in the design of both types of arrays in order to obtain the best-possible UWB performance. This article also discusses the fabrication and experimental validation of two 32-element linear polyfractal array-design prototypes, which exhibited close agreement to the radiation performance predicted by simulation. These experimentally validated arrays possessed wide bandwidths with suppressed grating lobes and relatively low sidelobes for their size (-16.3 dB at f(0), and -5.39 dB at 4f(0)). Additional simulations discussed in this paper showed that the benefits of these methodologies are amplified when applied to larger sized array designs (i.e., arrays with larger element counts). One example exhibited a peak sidelobe level less than -19.34 dB over a 40:1 bandwidth.