This letter introduces a novel, fast, efficient, and global optimization algorithm called hybrid invasive weed optimization and wind-driven optimization (IWO/WDO). The proposed algorithm is implemented to synthesize the uniformly excited (a _n = 1, Ø _n = 0) linear sparse array pattern having a minimum sidelobe level (SLL), and null control with constraint on beamwidth to minimize the interference effect by optimizing the element position-only. Three examples of (N = 10, 28, and 32)-element linear array synthesis are considered to illustrate the efficacy of the proposed algorithm. The results are compared to those obtained by IWO, WDO, PSO, CLPSO, DE, and BBO algorithms. Simulation studies demonstrate that this algorithm achieves minimum SLL of -23.5, -13.22, and -19.7 dB as compared to -17.35, -10.5, and -15.70 dB obtained by the IWO algorithm for 10-, 28-, and 32-elements array, respectively. Also, it yields a null depth level (NDL) larger than -84.5 dB in all cases. The learning characteristics show a faster convergence at around 100 iterations. The simulation results demonstrate the improved performance of hybrid IWO/WDO algorithm compared to other six algorithms in terms of null control, minimum SLL, beamwidth control, and the rate of convergence.

In this paper, a wideband Metamaterial Absorber (MA) is presented for various applications of X-band spectra. MA consists of an array of a unit cell arranged in a periodic fashion having two split square resonators printed on FR4 substrate whose relative permittivity is 4.4. The simulation result reveals that $-10$ dB absorption bandwidth of 5.98 GHz (from 5.94 GHz to 11.92 GHz) and the Full Width Half Maxima (FWHM) bandwidth of 7.55 GHz (from 5.58 GHz to 13.13 GHz). It has three peaks of absorption at 6.2, 8.1 and 11.1 GHz with Absorptivity of 99.59, 99.92 and 99.85 $\mathrm{\%}$, respectively. $0.095{\lambda }_0$ ${\lambda }_0$ The profile of absorber is low due to unit cell size dimensions of 9 mm×9 mm. The absorption mechanism is explained by taking effective electromagnetic parameters ( ${ϵ}_{\mathrm{e}\mathrm{f}\mathrm{f}}$ and ${\mu }_{\mathrm{e}\mathrm{f}\mathrm{f}}$) which are reacquired. The absorber has been investigated for a wide angle of oblique incidence and for different polarization angles as well. The proposed absorber is fabricated and its Absorptivity is tested experimentally.

In this article, a novel binary Wind Driven Optimization (WDO) algorithm is presented for the synthesis of six-band Metamaterial Absorber (MA). Synthesis of the unit cell structure of MA is done by optimizing the presence of each unit pixel of pixelated Frequency Selective Surface (FSS). Numerical simulation of this optimized absorber shows six discrete bands of absorptions at 7.6, 10.1, 13.3, 14.7, 15.8 and 16.7 GHz with more than 90% absorptivity under normal incidence of the wave. The proposed absorber is ultra-thin, polarization insensitive and has good performance over a wide angle of incidence. The numerical simulation and experimental results are in close agreement.