scholarly journals Design of a High-performance Flat Reflector Antenna Based on Conformal Transformation Optics

2022 ◽  
Author(s):  
Fateme Nazarzadeh ◽  
Abbas Ali Heidari
Keyword(s):  
Refractive Index ◽  
Conformal Transformation ◽  
High Performance ◽  
Refractive Index Profile ◽  
Side Lobe ◽  
Transformation Optics ◽  
Side Lobe Level ◽  
Graded Index ◽  
Index Approach ◽  
Simulation Results

Abstract In this paper, we design an implementable high-performance flat reflector based on conformal transformation optics. In the proposed 2-dimensional device, the rescaling refractive index approach is applied to overcome the sub-unit refractive index issue, resulting in an all-dielectric isotropic graded-index medium that is physically implementable. Rotating the permeability profile around the antenna axis yields the 3-dimensional profile of the flat reflector construction. The dielectric with continuous refractive index profile is split into eleven layers with a constant refractive index. The proposed antenna requires only dielectric layers with the permittivity of 1.1 to 3.8, making it realizable. Simulation results show that the proposed flat reflector can operate in wide frequency bandwidth. The simulated antenna gain is about 25.27 to 29.55 dBi in the 13-30 GHz frequency range with the side-lobe level below -15 dB. Design and simulation of the proposed antenna are done using COMSOL Multiphysics, and simulation results are validated with CST Studio Suite.

scholarly journals H-plane horn antenna with enhanced directivity using conformal transformation optics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hossein Eskandari ◽  
Juan Luis Albadalejo-Lijarcio ◽  
Oskar Zetterstrom ◽  
Tomáš Tyc ◽  
Oscar Quevedo-Teruel
Keyword(s):  
Conformal Transformation ◽  
Phase Error ◽  
Three Dimensional ◽  
Physical Space ◽  
Horn Antenna ◽  
High Gain ◽  
Transformation Optics ◽  
Graded Index ◽  
Low Profile ◽  
Dielectric Lens

AbstractConformal transformation optics is employed to enhance an H-plane horn’s directivity by designing a graded-index all-dielectric lens. The transformation is applied so that the phase error at the aperture is gradually eliminated inside the lens, leading to a low-profile high-gain lens antenna. The physical space shape is modified such that singular index values are avoided, and the optical path inside the lens is rescaled to eliminate superluminal regions. A prototype of the lens is fabricated using three-dimensional printing. The measurement results show that the realized gain of an H-plane horn antenna can be improved by 1.5–2.4 dB compared to a reference H-plane horn.

scholarly journals Null Steering in Failed Antenna Arrays

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Om Prakash Acharya ◽  
Amalendu Patnaik ◽  
Sachendra N. Sinha
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Side Lobe ◽  
Side Lobe Level ◽  
Correction Procedure ◽  
Swarm Optimization ◽  
Array Pattern ◽  
Null Steering ◽  
Simulation Results ◽  
Pattern Simulation

Antenna array pattern nulling is desirable in order to suppress the interfering signals. But in large antenna arrays, there is always a possibility of failure of some elements, which may degrade the radiation pattern with an increase in side lobe level (SLL) and removal of the nulls from desired position. In this paper a correction procedure is introduced based on Particle Swarm Optimization (PSO) which maintains the nulling performance of the failed antenna array. Considering the faulty elements as nonradiating elements, PSO reoptimizes the weights of the remaining radiating elements to reshape the pattern. Simulation results for a Chebyshev array with imposed single, multiple, and broad nulls with failed antenna array are presented.

Performance Evaluation of Elliptical-Cylindrical Antenna Array using SaDE Optimized Hyper Beam

2017 ◽  
Vol 7 (1) ◽  
pp. 178 ◽  
Author(s):  
Gebrehiwet Gebrekrstos Lema
Keyword(s):  
Communication Systems ◽  
High Performance ◽  
Optimization Technique ◽  
Analytical Techniques ◽  
Side Lobe ◽  
Optimization Techniques ◽  
Side Lobe Level ◽  
Pattern Synthesis ◽  
Improved Performance ◽  
The Individual

<p>For high performance communication systems, Side Lobe Level (SLL) reduction and improved directivity are the goal of antenna designers. In the recent years, many optimization techniques of antenna design are occupying demanding place over the analytical techniques. Though they have contributed attractive solutions, it is often obvious to select one that meets the particular design need at hand. In this paper, an optimization technique called Self-adaptive Differential Evolution (SaDE) that can be able to learn and behave intelligently along with hyper beam forming is integrated to determine an optimal set of excitation weights in the design of EcAA. Non-uniform excitation weights of the individual array elements of EcAA are performed to obtain reduced SLL, high directivity and flexible radiation pattern. To evaluate the improved performance of the proposed SaDE optimized hyper beam, comparison are done with uniformly excited, SaDE without hyper beam and Genetic Algorithm (GA). In general, the proposed work of pattern synthesis has resulted in much better reduction of SLL and FNBW than both the uniformly excited and thinned EcAA. The results of this study clearly reveal that the SLL highly reduced at a very directive beamwidth.</p>

Utilizing multimode interference effects in integrated graded-index optical waveguides for efficient power splitting

2018 ◽  
Vol 37 (4) ◽  
pp. 1556-1563 ◽  
Author(s):  
Jan-Philipp Roth ◽  
Thomas Kühler ◽  
Elmar Griese
Keyword(s):  
Refractive Index ◽  
Ion Exchange ◽  
Refractive Index Profile ◽  
Multimode Interference ◽  
Power Splitting ◽  
Index Profile ◽  
Content Type ◽  
Graded Index ◽  
Waveguide Components ◽  
Efficient Power

Purpose For the realization of optical waveguide components, needed for photonic integrated circuits, multimode-interference based (MMI-based) devices are an excellent component class for the realization of low loss optical splitters. A promising approach to the manufacturing of these components is their embedding in thin glass sheets by ion-exchange diffusion processes, which has not yet been extensively studied. This study aims to significantly enhance the modeling of the diffusion process to support manufacturing of graded-index, MMI-based optical splitters. Design/methodology/approach The methods of design and analysis of MMI-based components are based on a step-index refractive index profile. In this work, fundamental correlations between the properties of the manufacturing ion-exchange process and the characteristics of the graded-index, MMI-based components are established. The refractive index profile is calculated with a proprietary solver based on the finite element method. Any further investigation with respect to parameter influence is based on the beam propagation method, specifically a finite difference based, semi-vectorial, wide-angle beam propagation algorithm. The influence of the parameters of the self-imaging effect is investigated. On this basis, different approaches for efficient power splitting with graded-index, MMI-based waveguide components are evaluated. Findings Easy approximations – mostly linear – can be found to model the dependencies of the investigated parameters. The resulting graded-index splitters are characterized by their low excess and insertion loss. Originality/value These findings are the first step in the direction of the semi-analytical modeling of the respective waveguide components to reduce the numerical effort.

Nonparaxial diffraction-limited propagation of light in a graded-index planar medium with a hyperbolic secant refractive-index profile

2000 ◽  
Vol 39 (13) ◽  
pp. 2145 ◽  
Author(s):  
Carlos Gómez-Reino ◽  
María Victoria Pérez ◽  
Carmen Bao ◽  
María Teresa Flores-Arias ◽  
Silvia Vidal ◽  
...  
Keyword(s):  
Refractive Index ◽  
Refractive Index Profile ◽  
Index Profile ◽  
Graded Index ◽  
Propagation Of Light ◽  
Planar Medium

Formation of the refractive index profile in the graded index polymer optical fiber for gigabit data transmission

1997 ◽  
Vol 15 (11) ◽  
pp. 2095-2100 ◽  
Author(s):  
T. Ishigure ◽  
M. Satoh ◽  
O. Takanashi ◽  
E. Nihei ◽  
T. Nyu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Data Transmission ◽  
Refractive Index Profile ◽  
Index Profile ◽  
Polymer Optical Fiber ◽  
Graded Index

Non-Paraxial Diffraction-Free Propagation of Light in a Graded-Index Planar Waveguide with Hyperbolic Secant Refractive Index Profile

2000 ◽  
Vol 39 (Part 1, No. 3B) ◽  
pp. 1463-1467 ◽  
Author(s):  
Carlos Gomez-Reino ◽  
María Victoria Perez ◽  
Carmen Bao ◽  
María Teresa Flores-Arias ◽  
Silvia Vidal ◽  
...  
Keyword(s):  
Refractive Index ◽  
Planar Waveguide ◽  
Refractive Index Profile ◽  
Index Profile ◽  
Graded Index ◽  
Propagation Of Light ◽  
Free Propagation

scholarly journals Uniform Rectangular Array Synthesis and Optimization Using Modified Genetic Algorithm

2020 ◽  
Author(s):  
Mercy Sheeba J ◽  
S. Deepa
Keyword(s):  
Genetic Algorithm ◽  
Side Lobe ◽  
Beam Pattern ◽  
Side Lobe Level ◽  
Azimuthal Direction ◽  
Rectangular Array ◽  
Modified Genetic Algorithm ◽  
Simulation Results ◽  
Optimum Solution ◽  
Uniform Rectangular Array

This paper aims to synthesize a uniform rectangular array (URA) which spans beamwidth of -30∘ to 30∘ in the azimuthal direction with the interference direction as 40∘ in the azimuth plane. In this paper, a Modified Genetic Algorithm is proposed which works to produce a beam pattern with a narrow beamwidth, high directivity and maximized side lobe level (SLL) suppression. The simulation results for the proposed algorithm demonstrates that the synthesized beam pattern for a 16x16 URA at a frequency of 1 GHz converges to the desired optimum solution producing a maximum SLL suppression of -30dB.

scholarly journals Low Side Lobe Tapered Slot Antenna with High Gain Using Gradient Refractive Index Metamaterial for Ultra Wideband Application

2017 ◽  
Vol 6 (4) ◽  
pp. 63-69 ◽  
Author(s):  
R. Singha ◽  
D. Vakula
Keyword(s):  
Refractive Index ◽  
Beam Width ◽  
Parallel Line ◽  
Side Lobe ◽  
High Gain ◽  
Ultra Wideband ◽  
Slot Antenna ◽  
Side Lobe Level ◽  
Beam Focusing ◽  
Gradient Refractive Index

A broadband gradient refractive index (GRIN) metamaterial is used to improve the gain of the tapered slot antenna. The proposed metamaterial is capable of reducing the side lobe level of the antenna. The gradient refractive index (GRIN) metamaterial is constructed by using non-resonant parallel-line unit cells with different refractive index. Due to the non-resonant structure, the proposed unit cell exhibits low loss and large frequency bandwidth. The metamaterial, whose effective refractive index is lower than that of the substrate on which the antenna is printed. Therefore, the proposed metamaterial is act as a regular lens in beam focusing. The GRIN metamaterial is integrated in front of the antenna which has the capability to manipulate electromagnetic wave accurately. The measurement results indicate that the reflection coefficient of the antenna is below -10 dB over the frequency band from 3 to 11 GHz. The radiation pattern of the antenna shows the beam width becomes narrow and directive with low side lobe level. The peak gain is increased by 2.1 dB at 9.5 GHz.

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