Abstract-Circularly polarized superquadric dielectric resonator antenna is investigated. A single coaxial probe is used to excite circularly polarized patterns. Finite element method is used to analyze the problem. Different aspect ratios of the superquadric dielectric resonator cross section for each squareness parameter for circular polarization are calculated.
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.
Abstract-This paper presents a new enhancement technique for infrared images. This technique combines the benefits of homomorphic image processing and the additive wavelet transform. The idea behind this technique is based on decomposing the image into subbands in an additive fashion using the additive wavelet transform. This transform gives the image as an addition of subbands of the same resolution. The homomorphic processing is performed on each subband, separately. It is known that the homomorphic processing on images is performed in the log domain which transforms the image into illumination and reflectance components. Enhancement of the reflectance reinforces details in the image. So, applying this process in each subband enhances the details of the image in each subband. Finally, an inverse additive wavelet transform is performed on the homomorphic enhanced subbands to get an infrared image with better visual details.
Abstract-A Neural Network architecture is applied to the problem of Direction of Arrival (DOA) and state of polarization estimation using a uniform circular cross and tri-crossed-dipoles antenna array. A three layer Radial Basis Function Network (RBFN) is trained with input output pairs. The network is then capable of estimating DOA not included in the training set through generalization and the corresponding state of polarization. This approach reduces the extensive computations required by conventional super resolution algorithms such as MUSIC and is easier to implement in real-time applications. The results suggest that the performance of the RBFNN method approaches the exact values. In real time, fast convergence rates of neural networks will allow the array to track mobile sources.
The plasma reflectarray/transmitarray antenna is a planar array, which reflects/transmits the incident fields radiating from a feed antenna. The plasma introduces a reconfigurable material for antenna applications. The proposed reflectarray/transmitarray unit cell consists of two plasma cylindrical ring tubes positioned along the top and bottom of a plasma square ground plane filled with argon gas. By controlling the ionized plasma gas density of the square ground plane, two modes of operations are obtained, reflectarray and transmitarray modes for the same unit cell. A 13 × 13 unit cell reflectarray/transmitarray antenna covering an area of 13.52×13.52 cm 2 is proposed. The dimensions of the unit cells are identical with different argon gas densities according to the relative phases of the reflected/transmitted wave. The reflectarray is operating at 19.39 GHz, while the transmitarray is designed for 19.75-GHz applications. The radiation characteristics of the reflectarray/transmitarray single structure have been investigated. The gain and frequency bandwidth for the new configurations are presented. An electronic beam steering plasma transmitarray antenna from −30°to +30°is introduced. A full-wave analysis using the finite integration technique is used for design and analysis of the plasma reflectarray/transmitarray antenna.
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