A novel planar slot antenna is presented in this paper. The antenna provides dual-polarization and omnidirectional radiation patterns. Hence, it is suitable for hand-held equipments of wireless systems. The proposed antenna is optimized for operation at 5.2 GHz. The antenna, without ground plane extension, occupies an area of 2.17 2.17 cm . An impedance bandwidth of 10.6% is obtained, with a very good isolation between the two excitation ports. Appealing omnidirectional radiation patterns are maintained over the entire impedance bandwidth. The gains of the two polarizations are 2.59 and 3.52 dB, while the radiation efficiencies are 93% and 99.8%.

Abstract-The electromagnetic scattering from a conducting object coated with metamaterials, which have both negative permittivity and permeability is derived rigorously by using finite difference frequency domain (FDFD). A formulation for the FDFD method is presented. The scattering from circular and multilayers elliptic cylinder coated by metamaterial are investigated. Also, the scattering from dielectric and metamaterial sphere is depicted. Numerical results are compared with the available data in the literature.

Abstract-This paper presents a graphics processing based implementation of the Finite-Difference Frequency-Domain (FDFD) method, which uses a central finite differencing scheme for solving Maxwell's equations for electromagnetics. The radar cross section for different structures in 2D and 3D has been calculated using the FDFD method. The FDFD code has been implemented for the CPU calculations and the same code is implemented for the GPU calculations using the Brook+ developed by AMD. The solution obtained by using the GPU based-code showed more than 40 times speed over the CPU code.Corresponding author: E. El-Deen (emadtork@yahoo.com). 352Zainud-Deen et al.

The discrete complex image method stands as one of the most efficient techniques that is able to represent the Green's functions of multilayered structures accurately in the near-and intermediatefield regions. In order to extend the validity of the method to the far region, the surface waves are extracted. Although the extraction process yields accurate results in the intermediate and far-field regions, erroneous results are observed in the near-field region. In this paper, this problem is treated by extracting the contribution of an additional number of artificial poles. Using this scheme, the discrete complex image method can provide accurate representation of Green's functions in both the near-and far-field regions.

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