The aim of this paper is to introduce the grey wolf optimization (GWO) algorithm to the electromagnetics and antenna community. GWO is a new nature-inspired metaheuristic algorithm inspired by the social hierarchy and hunting behavior of grey wolves. It has potential to exhibit high performance in solving not only unconstrained but also constrained optimization problems. In this work, GWO has been applied to linear antenna arrays for optimal pattern synthesis in the following ways: by optimizing the antenna positions while assuming uniform excitation and by optimizing the antenna current amplitudes while assuming spacing and phase as that of uniform array. GWO is used to achieve an array pattern with minimum side lobe level (SLL) along with null placement in the specified directions. GWO is also applied for the minimization of the first side lobe nearest to the main beam (near side lobe). Various examples are presented that illustrate the application of GWO for linear array optimization and, subsequently, the results are validated by benchmarking with results obtained using other state-of-the-art nature-inspired evolutionary algorithms. The results suggest that optimization of linear antenna arrays using GWO provides considerable enhancements compared to the uniform array and the synthesis obtained from other optimization techniques.
A triple-notch band planar ultra-wideband (UWB) antenna is proposed for wireless body area networks (WBANs) to suppress unwanted signals of conventional narrow band communication technologies. These notch bands are WiMAX (3.3-3.8 GHz), WLAN (5.1-5.825 GHz), and X-band downlink satellite communication systems (7.25-7.75 GHz). A complementary split ring resonator slot and two L-shaped stubs are introduced on an elliptical-shaped radiating patch to obtain UWB coverage from 2.9 to 12 GHz with three notch bands. The overall antenna structure is fabricated on FR4 substrate with a size of 12 mm×19 mm which provides a size reduction of more than 42% with respect to recent literature. The simulated and measured results indicate that the proposed antenna is a good candidate for WBAN applications.
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