Taner Oguzer

Analysis of an arbitrary conic section profile cylindrical reflector antenna, H-polarization case

Two-dimensional scattering of waves by a perfectly electric conducting reflector having arbitrary smooth profile is studied in the H-polarization case. This is done by reducing the mixed-potential integral equation to the dual-series equations and carrying out analytical regularization. To simulate a realistic primary feed, directive incident field is taken as a complex source point beam. The proposed algorithm shows convergence and efficiency. The far field characteristics are presented for the reflectors shaped as quite large-size curved strips of elliptic, parabolic, and hyperbolic profiles.

Analysis of circular reflector antenna covered by concentric dielectric radome

The radiation from a two-dimensional cylindrical reflector antenna with a concentric dielectric radome is analyzed in an accurate manner for both H and E polarization cases. The problem is first formulated in terms of the dual series equations, and then it is regularized by using Riemann-Hilbert problem technique. The resulting matrix equation is solved numerically, with a guaranteed accuracy, and sufficiently little CPU time is needed. The feed directivity is included in the analysis by the complex source point method. Various characteristic patterns are obtained for the front-fed reflector antenna geometries in this study.

Analysis of the Nonconcentric Reflector Antenna-in-radome System by the Iterative Reflector Antenna and Radome Interaction

Nonconcentric reflector antenna-in-radome systems are used in applications especially requiring smaller radome coverages. The analysis of this two-dimensional geometry is performed for the E-polarization case. Here the geometry is decomposed into two parts and the analysis is performed by imposing the boundary conditions on each part as an iterative manner. This is known as the iterative boundary condition method in the literature. Convergence and accuracy are established numerically and it is seen that the expectations are really verified in reasonable CPU times. Also various numerical results are obtained for the description of the radiation characteristics.

Integral equation analysis of an arbitrary-profile and varying-resistivity cylindrical reflector illuminated by an E-polarized complex-source- point beam

A two-dimensional reflector with resistive-type boundary conditions and varying resistivity is considered. The incident wave is a beam emitted by a complex-source-point feed simulating an aperture source. The problem is formulated as an electromagnetic time-harmonic boundary value problem and cast into the electric field integral equation form. This is a Fredholm second kind equation that can be solved numerically in several ways. We develop a Galerkin projection scheme with entire-domain expansion functions defined on an auxiliary circle and demonstrate its advantage over a conventional moment-method solution in terms of faster convergence. Hence, larger reflectors can be computed with a higher accuracy. The results presented relate to the elliptic, parabolic, and hyperbolic profile reflectors fed by in-focus feeds. They demonstrate that a partially or fully resistive parabolic reflector is able to form a sharp main beam of the far-field pattern in the forward half-space; however, partial transparency leads to a drop in the overall directivity of emission due to the leakage of the field to the shadow half-space. This can be avoided if only small parts of the reflector near the edges are made resistive, with resisitivity increasing to the edge.

Analysis of the Nonconcentric Radome-Enclosed Cylindrical Reflector Antenna System, E-Polarization Case

Two-dimensional (2-D) radiation of a directive complex line source is analyzed in the presence of a perfectly conducting (PEC) reflector antenna system and nonconcentrically located dielectric radome. Similar problem was studied in the literature by using method of regularization and Greens function formulation for the H-polarization case. Here the same techniques are used for E-polarization case but in this case the scattered part of the Greens function is computed by using an FFT based algorithm. This provides us to solve the larger geometries accurately in reasonable computer times. So this approach can be considered as another alternative for the analysis of the E-polarized radome-enclosed reflector antenna system. Various numerical results are presented to support the convergence and accuracy of the technique and at the same time these results can be considered as reference data.

Focusing ability of a microsize graphene-based cylindrical reflector in the THz range illuminated by electromagnetic plane wave

The scattering of the H-polarized plane wave by a two-dimensional (2-D) parabolic reflector made of graphene placed in the free space is simulated by using the Method of Analytical Regularization (MAR) technique. The total scattering cross-section and absorption cross-section are computed, together with the field magnitude in the geometrical focus of reflector. The surface plasmon resonances are observed. Besides, the focusing ability of the reflector is studied in dependence of the chemical potential of the graphene.

Analysis of an arbitrary-profile, cylindrical, impedance reflector surface illuminated by an E-polarized complex line source beam

Electromagnetic scattering from a cylindrical reflector surface having an arbitrary conic section profile is studied. We assumed an electrically thin layer antenna illuminated by a complex line source in E-polarization mode. Our boundary value formulation, without loss of generality, involves an integral equation approach having impedance-type thin-layer boundary conditions. For simplicity, we also considered both faces of the reflector of the same uniform impedance value. Our computation employs the Method of Analytical Regularization (MAR) technique: the integral equations are converted into the discrete Fourier transform domain yielding two coupled dual series equations, which are then solved by the Fourier inversion and Riemann Hilbert Problem techniques. We demonstrate the accuracy and the convergence behaviors of our numerically solved MAR results that can serve as an accurate benchmark for comparison with widely used results obtained by approximate boundary conditions.

Analysis of an arbitrary conic section profile and thin dielectric cylindrical reflector illuminated by an E-polarized complex source point beam

We simulated arbitrary conic section profile and thin layer dielectric reflector using the Method of Analytical Regularization (MAR) techniques. The reflector is assumed to be illuminated by a complex source point type feed antenna in E-polarization mode. We obtained excellent accuracy and convergence of our simulation.

Analysis of a Cylindrical Reflector Antenna Encased in a Concentric Dielectric Radome With a Resistive or Pec Inner Circular Grating

A regularized solution is presented for a two-dimensional circular reflector antenna system inside a concentric dielectric radome reinforced by an inner resistive circular grating. The directive radiation pattern of the feed antenna is simulated by a Complex Point Source method. Furthermore for a very small resistivity case, an approximate solution for the same problem is presented by considering the grating material is made up of perfectly electric conductor. In this problem, the thickness of the dielectric radome may be arbitrary but the grating material thickness has to be very small compared to the free space wavelength. Various radiation characteristics are obtained and accuracy and convergence of the results are numerically verified. Furthermore, it is shown that a properly located two-element grating can be improving the overall directivity of the reflector antenna system.

Scattering and absorption performance of a microsize graphene-based parabolic reflector in the THz range illuminated by a complex line source

The scattering and absorption characteristics of a two- dimensional (2-D) parabolic reflector made of graphene and placed in the free space is simulated using the Method of Analytical Regularization (MAR) technique. Reflector is illuminated by a complex magnetic line source having a directive beam-like antenna pattern and placed in the geometrical focus of reflector. The total absorbed power and forward and backward directivities are computed. The surface plasmon (SP) resonances are observed. Besides, the scattering performance of the reflector is studied in dependence of the chemical potential of the graphene.