Sabry M. M. Ibrahem

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.

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

Performance of Circular Yagi-Uda Arrays for Beamforming Applications Using Particle Swarm Optimization Algorithm

In this paper, a circular Yagi-Uda array (CYUA) for smart antenna applications is designed using the lengths and spacings from the optimum design of a three-element linear Yagi-Uda antenna. Then a modified circular Yagi-Uda array (MCYUA) is developed by adding 5 circular connecting wires to the inner parasitic elements (reflectors) to form a wire grid cylinder. The results are compared with those for uniform circular array (UCA) with 12 half-wave dipole elements. In our analysis, the method of moments (MoM) is used to compute the response of the arrays in a mutual coupling environment. The particle swarm optimization (PSO) algorithm is used to optimize the complex excitations of the adaptive arrays elements for beamforming.

BUILT-IN DUAL FREQUENCY ANTENNA WITH AN EMBEDDED CAMERA AND A VERTICAL GROUND PLANE

Abstract—A thin internal planar antenna for GSM/DCS with a hollow shorting cylinder suitable for integration with an embedded digital camera for a mobile phone is presented. A small vertical ground plane electrically connected to the system ground plane of the mobile phone is used. The vertical ground plane can function as an effective shield wall between the antenna and the nearby electronic elements in the mobile phone. The method of moments is used to simulate the antenna structure and calculate the radiation characteristics of the antenna.

MPSO-MOM: A Hybrid Modified Particle Swarm Optimization and Method of Moment Algorithm for Smart Antenna Synthesis

Abstract In this article, a modified version of particle swarm optimization (MPSO) and the method of moment (MOM) are combined to achieve the beamforming objective of a practical smart antenna array. The hybrid approach (MPSO–MOM) is illustrated by application to a planar uniform circular array (PUCA) with 30 elements of half-wave dipoles. The array feeding is optimized by MPSO, and the fitness function is evaluated by MOM simulations. The MOM is used to calculate the response of the array in a mutual coupling environment. The performance of the adaptive array using discrete (quantized) feedings is studied. Also in this article, the convergence capability of the MPSO is compared with that of the classical particle swarm optimization and other recent evolutionary-based algorithms using benchmark examples and a linear array synthesis problem.

Investigation of an octafilar helix antenna

An octafilar helix antenna for circular polarization (CP) is proposed and theoretically investigated. The moment method is applied to find the rigorous solutions of the current distributions on bifilar, quadrifilar and octafilar helix antennas of different helix lengths. Comparisons of calculated and available experimental results for quadrifilar helix antenna are presented, indicating good agreement. Cardioid shaped radiation pattern with excellent circular polarization over a wide angle for octafilar helix antenna is obtained. For 1/2 turn octafilar helix antenna, the axial ratio is less than 3 dB for θ ranging from −65 to 65 degrees, while the gain varies from 1.76 dB at θ=−65° to 5.34 dB at θ=0°.An octafilar helix antenna for circular polarization (CP) is proposed and investigated theoretically. The moment method is applied to find the rigorous solutions of the current distributions on bifilar, quadrifilar and octafilar helix antennas of different helix lengths. Comparisons of calculated and available experimental results for a quadrifilar helix antenna are presented, indicating good agreement. A cardioid shaped radiation pattern with excellent circular polarization over a wide angle is obtained for the octafilar helix antenna. For a 1/2 turn octafilar helix antenna, the axial ratio is less than 3 dB for /spl theta/ ranging from -65 to 65 degrees, while the gain varies from 13.7 dB at /spl theta/=-65/spl deg/ to 16.5 dB at /spl theta/=0/spl deg/. The radiation characteristics of an octafilar helix antenna on a conducting box are illustrated.

Radial Basis Function Neural Networks for Filling the MoM Impedance Matrix

In this paper radial basis function neural network (RBF-NN) used for filling the method of moments (MoM) impedance matrix of several configuration of wire antennas. Four radial basis function neural networks (RBF-NNs) are trained to calculate the impedances of two elements consist of four monopoles. The mutual impedance between the two elements is the sum of outputs of the four RBF-NNs. The RBF-NN model is applied to the analysis of the straight dipole, two element array, circular array, wire-grid corner reflector, square loop, and square spiral antenna

Multifilar-curl antenna

Multifilar-curl antennas that can radiate circularly polarized waves are analyzed in detail. The antenna is fed directly or electromagnetically coupled by an inverted-L wire section to improve its impedance matching. The method of moments (MoM) is used to model the antenna structure in the presence of an infinite ground plane. The radiation characteristics of a single curl antenna are compared with available measurements to validate the analysis. A quadrifilar-curl antenna on an infinite ground plane is considered. The current distribution along the antenna, the radiation patterns, the axial ratio, the antenna gain, the input impedance, and VSWR are calculated. An octafilar-curl antenna on an infinite ground plane is proposed to increase the gain of the antenna and to improve the circular polarization characteristics. Also, quadrifilar- and octafilar-curl antennas without a ground plane are presented. The radiation characteristics are calculated. The frequency response of the input impedance, VSWR and the antenna gain are depicted.

Ultrawideband printed elliptical monopole antenna with four band-notch characteristics

In this paper, a compact ultrawideband (UWB) elliptical monopole antenna with four band-notched characteristics is proposed. An optimized half elliptical slit is inserted into the ground plane to improve the impedance bandwidth. The proposed antenna can be achieving separately four sharp notches at frequencies 3.5 GHz, 5.5 GHz, 9.GHz and 12.5 GHz. The simulation is performed using the finite-difference time-domain technique. The proposed antenna has an acceptable omnidirectional radiation pattern. The results prove that this kind of antenna not only satisfies all UWB but also rejects the limited bands in order to avoid possible interference with existing wireless networks.

Overlapped printed monopole antennas for ultrawideband applications

Configurations of overlapped rectangular patches printed antennas with a slitted ground plane have been investigated. Three overlapped patches are used. The effect of overlapping patches on the impedance bandwidth, input impedance, VSWR, gain and radiation patterns has been studied. Elliptical slit in the ground plane is used to improve the impedance bandwidth of the antenna. Overlapping slots are cut in the radiating surface to reduce the size of the metal material of the antenna. The proposed structure provides 13.3 GHz bandwidth for 10-dB return loss ranging from 3.1 to 16.4 GHz. The simulated radiation patterns are also shown as well. The proposed antenna features UWB behavior with near omnidirectional characteristics and good radiation efficiency.