A-K. Hamid

Electromagnetic scattering by a lossy dielectric elliptic cylinder

The problem of electromagnetic wave scattering by a lossy dielectric elliptic cylinder is analyzed using an exact series solution in terms of the Mathieu functions. A special computer code based on the eigenfunction technique was developed to compute complex Mathieu function and was used with the solution of dielectric elliptic cylinder to produce numerical results for the scattered field in the far zone for different axial ratio, lossy dielectric constants, and angle of incidence.

Simulation of CPW bow-tie aperture antenna loaded with metal strips

A CPW bowtie aperture antenna loaded with metal strips is presented to operate at tri-band frequencies: 8.45, 9.5 and 10.8 GHz. The new frequencies are achieved without increasing the size of the original unloaded antenna. The new antenna is loaded with 16 rectangular strips of different sizes to operate at tri-band frequencies. The antenna is symmetrical to CPW feed. The simulated results using HFSS are obtained for reflection coefficients, radiation patterns and impedances for loaded and unloaded antennas. The results show that new lower operating frequencies can be achieved without increasing antenna size.

Radiation Characteristics of a Spheroidal Slot Antenna Coated with Isorefractive Materials

This paper presents an exact analytic solution to the problem of radiation from an axisymmetric slot antenna on a conducting prolate spheroid coated with an isorefractive material, when the slot is excited by a delta gap source. The problem is formulated by expanding the electromagnetic field in each region in terms of appropriate spheroidal vector wave functions and a set of unknown expansion coefficients, and imposing boundary conditions at the interface between the conducting spheroid and the isorefractive coating, as well as that between the coating and the medium outside the coating. This generates a set of simultaneous linear equations, the solution of which yields the unknown expansion coefficients. Results are presented in the form of normalized power patterns for conventional isorefractive materials as well as for isorefractive metamaterials, and for different slot locations, to show the enhancing effects of the coating on the radiation from the antenna.

Multi-frequency CPW bow-tie aperture antenna with rectangular and U shape metal strips

This paper presents a new design for aperture bowtie antenna with added rectangular and U shape metal strips to function at new different frequencies: 8.2, 9.25 and 10.5 GHz. The advantage of the proposed design is to use the original antenna shape and its dimensions to achieve the multiple frequencies. The proposed design consists of adding 2 U shape metal strips of similar sizes as well as 4 rectangular metal strips of different sizes for the original antenna. HFSS software is used in the simulation of the antenna in order to obtain reflection coefficients, radiation patterns, impedances and surface current distributions.

Scattering by PEMC elliptic cylinder loaded by metamaterial coating

Exact analytic solution is presented to the problem of scattering by perfect electromagnetic conducting (PEMC) elliptic cylinder coated by metamaterial due to a plane wave illumination. The problem is formulated by expanding the various fields in terms of appropriate angular and radial Mathieu functions and a set of expansion coefficients. The expansion coefficients associated with the incident fields are known, where those associated with the fields inside and outside the coating are unknown. Imposing the boundary conditions at the surface of the elliptic cylinder and the surface of the coating leads to determination of the unknown expansion coefficients. Results are presented for the normalized scattering widths of elliptic cylinders with various sizes, PEMC admittances and different coatings, to show the effects of these on scattering.

Radar cross section of a system of conducting spheres each coated with a dielectric layer

Analytical solution to the problem of scattering of a plane electromagnetic wave by an array of conducting spheres each coated with a dielectric layer is derived. The incident, scattered and transmitted electric and magnetic fields are expressed in terms of the vector spherical wave functions. The vector spherical translation addition theorem is applied to impose the boundary conditions on the surface of each dielectric‐coated sphere. Numerical results are computed and presented graphically for the radar cross of several configurations of dielectric‐coated spheres.

Hexa-Band MIMO CPW Bow-Tie Aperture Antenna using Particle Swarm Optimization

Basis test paths is a method that uses a graph contains nodes as a representation of codes and the lines as a sequence of code execution steps. Determination of basis test paths can be generated using a Genetic Algorithm, but the drawback was the number of iterations affect the possibility of visibility of the appropriate basis path. When the iteration is less, there is a possibility the paths do not appear all. Conversely, if the iteration is too much, all the paths have appeared in the middle of iteration. This research aims to optimize the performance of Genetic Algorithms for the generation of Basis Test Paths by determining how many iterations level corresponding to the characteristics of the code. Code metrics Node, Edge, VG, NBD, LOC were used as features to determine the number of iterations. J48 classifier was employed as a method to predict the number of iterations. There were 17 methods have selected as a data training, and 16 methods as a data test. The system was able to predict 84.5% of 58 basis paths. Efficiency test results also show that our system was able to seek Basis Paths 35% faster than the old system.A single-fed linearly polarized 2x2 microstrip bow tie array antenna is proposed. The feed network has microstrip line and slot line where microstrip-slot branch circuit is connected in parallel. The feed network of the array is designed using both-sided MIC Technology to overcome the impedance matching problem of conventional feed networks. The 2x2 half bow tie array antenna is also truncated with spur lines for optimization of antenna performance. The array antenna unit can be realized in very simple and compact structure, as all the antenna elements and the feeding circuit is arranged on a Teflon glass fiber substrate without requiring any external network. The design frequency of the proposed antenna is 5 to 8 GHz (C-Band) and the obtained peak gain is 12.41 dBi. The resultant axial ratio indicates that linear polarization is achieved.This paper presents a novel method for QRS detection. To accomplish this task ECG signal was first filtered by using a third order Savitzky Golay filter. The filtered ECG signal was then preprocessed by a Wavelet based denoising in a real-time fashion to minimize the undefined noise level. R-peak was then detected from denoised signal after wavelet denoising. Windowing mechanism was also applied for finding any missing R-peaks. All the 48 records have been used to test the proposed method. During this testing, 99.97% sensitivity and 99.99% positive predictivity is obtained for QRS complex detection.

Penta-frequency CPW bow-tie aperture antenna for mobile communications

A penta-band frequency bowtie antenna design is presented to operate at five different frequencies: 5 (WLAN), 5.7 (WLAN), 6.8, 8.65 and 11 GHz for mobile and wireless communications. The additional frequencies resulted from adding 3 metallic strips of different sizes to both sides of the aperture bowtie antenna. Two pairs of strips have the same dimensions while the other two strips are unequal and vary vertically. The simulation of the design was performed using HFSS software to obtain the reflection coefficients, radiation patterns, impedances and surface current distributions.

Scattering by a chiral elliptic cylinder placed in another infinite chiral medium

Analytic solution is presented to the problem of scattering of a plane wave from a chiral elliptic cylinder placed in another infinite chiral medium, using the method of separation of variables. The incident, scattered as well as the transmitted electromagnetic fields are expressed in terms of appropriate angular and radial Mathieu functions with expansion coefficients. The scattered and transmitted field expansion coefficients are determined by imposing the boundary conditions at the surface of the chiral-chiral elliptic cylinder. Results are presented graphically for the normalized scattering widths for elliptic cylinders of different sizes and chiral materials to show the effects of these on scattering cross widths.

Metamaterial coated slotted elliptic antenna embedded partially in a ground plane

Radiation characteristics of an axially slotted elliptic antenna coated by conventional dielectric or metamaterial material embedded partially in a ground plane are investigated analytically. The field in each region is expressed in terms of appropriate radial and angular Mathieu functions with unknown field coefficients. The boundary conditions at the conducting, dielectric coating and ground plane surfaces are enforced to obtain the unknown field expansion coefficients numerically. Results are plotted for the radiation pattern to show the effect of the presence of the ground plane and different coatings.