S.H. Zainud-Deen

A Comparison Between Circular and Hexagonal Array Geometries for Smart Antenna Systems Using Particle Swarm Optimization Algorithm

In this paper, circular and hexagonal array geometries for smart antenna applications are compared. Uniform circular (UCA) and hexagonal arrays (UHA) with 18 half-wave dipole elements are examined; also planar (2 concentric rings of radiators) uniform circular (PUCA) and hexagonal arrays (PUHA) are considered. The effect of rotating the outer ring of the PUCA is studied. In our analysis, the method of moments is used to compute the response of the uniform circular and hexagonal dipole arrays in a mutual coupling environment. The particle swarm optimization (PSO) algorithm is used to optimize the complex excitations, amplitudes and phases, of the adaptive arrays elements for beamforming.

Microstrip Antenna with Defected Ground Plane Structure as a Sensor for Landmines Detection

A proposed sensor for landmines detection consists of two parallel microstrip antennas placed on the same ground plane and with defected ground structure between them has been investigated. The microstrip patch array with defected ground structure has the advantage of a low mutual coupling compared with the classic one. The Finite-Difference Time-Domain (FDTD) is used to simulate the sensor for landmines detection.

A Single-Feed Cylindrical Superquadric Dielectric Resonator Antenna for Circular Polarization

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.

INVESTIGATING THE INTERACTION BETWEEN A HUMAN HEAD AND A SMART HANDSET FOR 4G MOBILE COMMUNICATION SYSTEMS

In this paper we evaluate the potential of a 5-element monopole array incorporated into a handheld device for beamforming in the 5.0-GHz band. The geometry of the handset consists of a 5-element array: four elements located at the handset corners and the fifth-element located at the center. Also, the interaction of the antenna array, mounted on a mobile handset, with a human head phantom is investigated. Firstly, the spatial peak specific absorption rate (SAR) values of 5-element array antennas for mobile handsets in the vicinity of a spherical phantom of a human head are evaluated numerically as a function of the distance between the handset and the head phantom for two different scenarios. Next, the effect of the human head on the handset radiation pattern is studied. The effect of different handset positions on the radiation pattern is also considered. The particle swarm optimization (PSO) algorithm is used to optimize the complex excitations of the adaptive arrays elements in a mutual coupling environment for beamforming synthesis. All numerical simulations are performed using the FEKO Suite 5.3

ELECTROMAGNETIC SCATTERING USING GPU-BASED FINITE DIFFERENCE FREQUENCY DOMAIN METHOD

This paper presents a graphics processing based im- plementation of the Finite-Difierence Frequency-Domain (FDFD) method, which uses a central flnite difierencing scheme for solving Maxwells equations for electromagnetics. The radar cross section for difierent structures in 2D and 3D has been calculated using the FDFD method. The FDFD code has been implemented for the CPU calcu- lations 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.

Scattering from bodies coated with metamaterial using FDFD method

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.

Array failure correction with orthogonal method

The orthogonal method is used to improve the patterns of the linear array in the presence of failed elements. Reconfiguration of the amplitude and phase distributions of the remaining elements can partially compensate for the failed elements and thus reduce the sidelobe level. Numerical results are presented to illustrate the effectiveness of the method. The effect of the number of failed elements, the distance between the elements and the shape of the desired pattern is demonstrated through this paper.

Controlled Radiation Pattern of Circular Antenna Array

This paper presents a seven-element dipole circular array with different lengths and separation between the elements that was used to produce maximum gain in certain directions. The method of moments was used to formulate the problem. The radiation characteristics of the array were calculated, considering that one element acts as an active element while the others to act as parasitic elements. The genetic algorithm was used to optimize the dimensions and the separation between the elements

Transmitarray Using Perforated Dielectric Material for Wideband Applications

In this paper, linearly polarized transmitarray is investi- gated as to avoid the usage of multi-layers for improving the bandwidth of transmitarray. The transmitarray is formed from a single dielectric sheet by perforating selected areas of the material. A perforated dielec- tric layer is divided into square cell elements. Each cell has four holes with the same diameters. Holes with difierent diameters in the cell el- ements are used to allow continuous tuning of the transmitted signals phase over 360 - range with a maximum loss of 3.6dB at 10GHz. The transmission coe-cient versus the diameter of the holes is calculated by using the flnite integration technique. The results are compared with those calculated with transmission line method for veriflcation. The focal-to-diameter ratio of the transmitarray is optimized for lower side lobe level and highest transmitarray gain. A comparison between the transmitarray and the re∞ectarray with the same aperture area is illustrated.

Microstrip antenna with corrugated ground plane surface as a sensor for landmines detection

A proposed sensor for landmines detection consists of two parallel microstrip antennas placed on the same ground plane and with corrugated ground surface between the arrays has been investigated. The microstrip patch array with corrugated ground surface has the advantage of a low mutual coupling compared with the classic arrays. The finite-difference time-domain (FDTD) is used to simulate the sensor for landmines detection.