There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Neural networks

Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.

Gain enhancement methods for printed circuit antennas

This paper focuses on a tutorial overview of defected ground structure (DGS). The basic conceptions and transmission characteristics of DGS are introduced and the equivalent circuit models of varieties of DGS units are also presented. Finally, the main applications of DGS in microwave technology field are summarized and the evolution trend of DGS is given.

/pdf/an-overview-on-defected-ground-structure-3dt7yj00ew.pdf

An Overview on Defected Ground Structure

[신간안내] Computational Electrodynamics (the finite difference time - domain method)

A hybrid technique based on finite-difference frequency domain (FDFD) and particle swarm optimization (PSO) techniques is proposed to reconstruct the angular crack width and its position in the conductor and ability to detect the crack width, position, and its depth in single and multilayer dielectric objects. FDFD is formulated to calculate the scattered field after illuminating the object by a microwave transmitter. Two-dimensional model for the object is used. Computer simulations have been performed by means of a numerical program; results show the capabilities of the proposed approach. This paper presents a computational approach to the two dimensional inverse scattering problem based on FDFD method and PSO technique to determine the crack position, width and depth. By using the scattered field, the specifications of the crack are reconstructed.

/pdf/breast-cancer-detection-using-a-hybrid-finite-difference-2iz6jkumzd.pdf

Breast cancer detection using a hybrid Finite difference frequency domain and particle swarm optimization techniques

This paper presents a new application of dielectric resonator antenna in radio frequency identification system. A curved dual-band dielectric resonator antenna for RFID applications is proposed. The tag antenna is designed to operate at 2.45 GHz (2.25– 2.55 GHz) and 5.8 GHz (5.65– 5.95 GHz) bands. The radiation characteristics of the tag antenna in free space are investigated. The radar cross sections under different loads are obtained. The effect of curvature on the tag antenna performance is explained. Two examples are considered. In the first example, the tag antenna is mounted on cylindrical bottle filled with the Palmitic Acid material or water like materials. The effect of the object properties on the radiation characteristics and the radar cross section is investigated. In the second example, the tag antenna is mounted on spherical bottle filled with the Palmitic Acid material. The radiation and backscattering characteristics are calculated. The Finite Element Method (FEM) is used for simulation and the Finite Integration Technique (FIT) is used to verify the simulated results.

/pdf/curved-dual-band-dielectric-resonator-tag-antenna-for-rfid-2hk26ra2de.pdf

Curved dual- band dielectric resonator tag antenna for RFID applications

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

/pdf/microstrip-antenna-with-defected-ground-plane-structure-as-a-5ap0btcuo6.pdf

Microstrip antenna with defected ground plane structure as a sensor for landmines detection

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.

/pdf/a-single-feed-cylindrical-superquadric-dielectric-resonator-18lm2wwfhu.pdf

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

A technique for computing the input impedance of a monopole on a finite ground plane is provided. The case of an infinite ground plane is first examined, and then the concept of using a magnetic edge current as an equivalent source of diffraction on the limited size ground plane is introduced. The technique used is serf-consistent in that the circular ground plane considered is the limit of a polygonal ground plane as the number of sides tends to infinity. Good agreement has been demonstrated when the nearest edge of the ground plane is at least 0.3 wavelength from the base of the monopole.

Kamal H. Awadalla

Papers

Breast cancer detection using a hybrid Finite difference frequency domain and particle swarm optimization techniques

Curved dual- band dielectric resonator tag antenna for RFID applications

Microstrip antenna with defected ground plane structure as a sensor for landmines detection

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

Input impedance of a monopole antenna at the center of a finite ground plane