Showing papers by "Qaisar Abbas Naqvi published in 2007"
TL;DR: In this article, the scattering of electromagnetic plane wave by a perfectly conducting disk is formulated rigorously in a form of the dual integral equations (abbreviated as DIE), where the unknowns are the induced surface current and the tangential components of the electric field on the disk.
Abstract: The scattering of electromagnetic plane wave by a perfectly conducting disk is formulated rigorously in a form of the dual integral equations (abbreviated as DIE). The unknowns are the induced surface current (or magnetic field) and the tangential components of the electric field on the disk. The solution for the surface current is expanded in terms of a set of functions which satisfy Maxwell's equation for the magnetic field on the disk and the required edge condition. At this step we have used the method of the Kobayashi potential and the vector Hankel transform. Applying the projection solves the rest of a pair of equations. Thus the problem reduces to the matrix equations for the expansion coefficients. The matrix elements are given in terms of the infinite integrals with a single variable and these may be transformed into infinite series that are convenient for numerical computation. The numerical results are obtained for far field patterns, current densities induced on the disk, transmission coefficient through the circular aperture, and radar cross section. The results are compared with those obtained by other methods when they are available, and agreement among them is fairly well.
79 citations
TL;DR: In this article, high frequency field expressions are derived around feed point of a three dimensional Cassegrain system using the Maslov's method, which combines the simplicity of ray theory and generality of the transform method.
Abstract: High frequency field expressions are derived around feed point of a three dimensional Cassegrain system using the Maslov’s method. Maslov’s method is a systematic procedure for predicting the field in the caustic region. It combines the simplicity of ray theory and generality of the transform method. Numerical computations are made for the analysis of field pattern around the caustic of a Cassegrain system.
42 citations
TL;DR: In this article, the scattering of electromagnetic plane wave from an impedance strip is investigated using Kobayashi potential, which uses the discontinuous properties of Weber-Schafheitlin's integrals.
Abstract: This paper investigates the scattering of electromagnetic plane wave from an impedance strip. Both Eand H-polarizations are considered. The method of analysis is Kobayashi potential, which uses the discontinuous properties of Weber-Schafheitlin’s integrals. Imposition of boundary conditions result in dual integral equations. Using the projection, equations reduces to matrix equations. The elements are given in terms of infinite integrals that contains the poles for particular values of surface impedance and these integrals are computed numerically. Far diffracted fields in the upper half space for different angles of incident are computed. To check the validity of the results, we have derived the physical optics (PO) approximate solutions. Numerical results for both the methods are compared. The agreement is good. Current distribution on the strip is also presented.
40 citations
TL;DR: Fractional dual rectangular waveguides may be considered as intermediate of two given wave-guides, where both wave-guide are related through principle of duality as mentioned in this paper, and the behavior of field lines in transverse plane is also investigated.
Abstract: Fractional curl operator is utilized to construct the solutions corresponding to fractional dual rectangular waveguides. Fractional dual rectangular waveguides may be considered as intermediate of two given waveguides, where both waveguides are related through principle of duality. Characteristic impedance of fractional waveguide is determined. Behavior of field lines in transverse plane is also investigated.
40 citations
TL;DR: In this article, a fractional parallel plate chiro-waveguide has been used to study the wave propagation through a waveguide and the impedance of the walls of the chiro waveguide was determined.
Abstract: Fractional curl operator has been utilized to study the wave propagation through a fractional parallel plate chiro-waveguide. Chiro-waveguide is the waveguide filled with homogeneous, isotropic chiral material. Fractional dual solutions have been established for fractional chiro-waveguide. Using these solutions for electric and magnetic fields, impedance of the walls of the fractional chiro-waveguide has been determined. It is observed that waveguide with perfect electric conducting walls and waveguide with perfect magnetic conducting walls are the two limiting cases, while the solutions for non-integer values yield the waveguide with impedance walls. Impedance of walls of the fractional chiro-waveguide has been found periodic with respect to the fractional parameter α.
38 citations
TL;DR: In this article, the fractional perfect electromagnetic conducting waveguide may be regarded as intermediate step between the two given waveguides, and corresponding fields and surface impedance have been determined and boundary conditions for DPEMC surface have been derived.
Abstract: Fractional curl operator has been utilized to study the fractional perfect electromagnetic conducting waveguide. The fractional perfect electromagnetic conducting waveguide may be regarded as intermediate step between the two given waveguides. One of the waveguide is composed of perfect electromagnetic conducting (PEMC) walls while other is dual of it as (DPEMC). Corresponding fields and surface impedance have been determined and boundary conditions for DPEMC surface have been derived.
38 citations
TL;DR: In this article, high frequency field expressions for a two-dimensional reflector are derived for a homogeneous and reciprocal chiral medium, where the reflector is placed in a homogenous and reciprocal Chiral medium.
Abstract: High frequency field expressions for a two dimensional reflector are derived. The reflector is placed in a homogenous and reciprocal chiral medium. Since geometrical optics fails at caustics so Maslovs method has been used to find the field expressions which are also valid around caustics. Examples of parabolic and circular reflectors have been considered.
31 citations
TL;DR: Using fractional curl operator, impedance of the surface which may be regarded as intermediate step between the perfect elec- tromagnetic conductor (PEMC) and dual to the perfect electromagnetic conductor (DPEMC), has been determined as mentioned in this paper.
Abstract: Using fractional curl operator, impedance of the surface which may be regarded as intermediate step between the perfect elec- tromagnetic conductor (PEMC) and dual to the perfect electromag- netic conductor (DPEMC) has been determined. The results are com- pared with the situation which is intermediate step ofperfect electric conductor (PEC) and perfect magnetic conductor (PMC).
30 citations
TL;DR: In this article, the field refracted by a Wood lens is determined analytically and numerically in the focal region by Maslov's method and compared with those obtained by weak focusing approximation and Kirchhoff's diffraction integral.
Abstract: The field refracted by a Wood lens is determined analytically and numerically in the focal region by Maslov’s method. Results are compared with those obtained by weak focusing approximation and Kirchhoff’s diffraction integral. Agreement among them is fairly good when the parameters satisfy the conditions associated to the approximation.
27 citations
11 Apr 2007
TL;DR: In this paper, the Held radiated from n fractional elementary current dipole was determined and the fractional source may be regarded as intermediate between the electric and magnetic dipole.
Abstract: We have determined the Held radiated from n fractional elementary current dipole. Fractional source may be regarded as intermediate between the electric and magnetic dipole. The fractional dipole source is located in homogeneous and reciprocal chiral medium.
1 citations