. Improving the performances of a high Tc superconducting circular microstrip antenna with multilayered configuration and anisotropic dielectrics. Progress In Electromagnetics Research, EMW Publishing, 2010, vol. 18, pp 169-183. Progress In Electromagnetics Research C, Vol. 18, 169-183, 2011 IMPROVING Abstract-The moment method technique has been improved to investigate the scattering properties of high T c superconducting circular antennas with anisotropic substrate in multi-layered configuration. In this method, the electric field integral equation for a current element on a grounded dielectric slab of infinite extent was developed by basis functions involving Chebyshev polynomials. An improved analytical model is presented taking into account anisotropic substrate, superconducting material for the circular patch and multilayered structure. To validate the theoretical results, an experimental study has been performed for a perfectly conducting circular patch on a single layer, with and without air gap. Good agreements were obtained between our theory and measurements. Effects of temperature and thickness of a superconducting film are also reported and discussed. The performances of high T c superconducting circular antennas were improved by the use of uniaxial anisotropy substrate and multilayer configuration.

Abstract-Two 2-D natural fractal monopoles generated by electrodeposition are characterized in term of measured return loss. Depending on their different shapes, previously reported multiband behaviour and new ultra-wideband (UWB) characteristics are obtained. Finally, sufficient efficiencies are measured for both antennas proving their possible use as radiating element.

The aim of this work is to show the effectiveness of a new algorithm named as modified grey wolf optimization (MGWO) algorithm to determine the optimum combination parameters values of a linear antenna array which is widely used in the communication systems. The selection part of the classical GWO has been modified by adopting the competitive exclusion selection inspired from genetic algorithm. The objective to be attained is a directional array factor with a very low level of lateral lobs. To this effect, a Gaussian function centered at 90° with the total absence of secondary lobs is considered as a desired diagram in our simulation. To matches the desired pattern as closely as possible, we considered the optimization of interspacing elements, weights amplitude and phase excitation of the linear antenna array factor. It has been demonstrated that the performance of a printed linear antenna array depends on all parameters, in which simultaneous optimization is imperative to maximize its characteristics. The obtained results show the effectiveness and the flexibility of the proposed algorithm in terms of minimized lateral lobe level compared to PSO algorithm and the convergence speed towards the desired solution.

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