Half Maxwell Fish-eye Research Articles

Wideband Multibeam Shared-Aperture Geodesic Half-Maxwell Fish-Eye Lens Antenna Based on 3-D Printed Technology for 5G Applications

Wideband Multibeam Shared-Aperture Geodesic Half-Maxwell Fish-Eye Lens Antenna Based on 3-D Printed Technology for 5G Applications

Unveiling New IoT Antenna Developments: Planar Multibeam Metasurface Half-Maxwell Fish-Eye Lens with Wavelength Etching

This study introduces a groundbreaking antenna system, the directive Metasurface Half-Maxwell Fish-Eye (MHMF) lens antenna, tailored specifically for Internet-of-Things (IoT) networks. Designed to operate at 60 GHz, this antenna ingeniously integrates a dipole antenna within a parallel-plate waveguide to illuminate a Half-Maxwell Fish-Eye (HMFE) lens. The HMFE lens serves as a focal point, enabling a crucial high gain for IoT operations. The integration of metasurface structures facilitates the attainment of the gradient refractive index essential for the lens surface. By employing commercial Ansys HFSS software, extensive numerical simulations were conducted to meticulously refine the design, focusing particularly on optimizing the dimensions of unit cells, notably the modified H-shaped cells within the parallel waveguides housing the beam launchers. A functional prototype of the antenna was constructed using a standard PCB manufacturing process. Rigorous testing in an anechoic chamber confirmed the functionality of these manufactured devices, with the experimental results closely aligning with the simulated findings. Far-field measurements have further confirmed the effectiveness of the antenna, establishing it as a high-gain antenna solution suitable for IoT applications. Specifically, it operates effectively within the 60 GHz range of the electromagnetic spectrum, which is crucial for ensuring reliable communication in IoT devices. The directive HMFE lens antenna represents a significant advancement in enhancing IoT connectivity and capabilities. Leveraging innovative design concepts and metasurface technology, it heralds a new era of adaptable and efficient IoT systems.

Wideband high gain SIW horn antenna loaded with half Maxwell fish‐eye fabricated by 3‐D‐printing

AbstractThis letter presents a wideband high gain substrate integrated waveguide horn antenna (SIWHA) loaded with half Maxwell fish‐eye (HMFE) fabricated by 3‐D‐Printing. The impedance bandwidth of the SIWHA is narrow, mainly caused by the discontinuity between the substrate with the air. By introducing the HMFE and a match layer between the SIWHA with HMFE, the impedance continuity can be realized, which can not only improve the impedance bandwidth but also enhance the antenna gain. Experimental results show that the proposed antenna can achieve more than 6 dBi gain and 60.9% relative impedance bandwidth with reflection coefficients lower than −10 dB.

Ultra-broadband on-chip beam focusing enabled by GRIN metalens on silicon-on-insulator platform.

Metalens has emerged as an important optical block in free-space optical systems, which shows excellent performance. Even the metalens based on gradient index (GRIN) profiles can be implemented for on-chip beam focusing behavior. However, for most previous schemes, the GRIN metalenses can only achieve on-chip beam focusing behavior in one dimension, which limits their applications in low-loss waveguide interconnecting or fiber-to-chip coupling. In this paper, an on-chip half Maxwell's fisheye lens based on GRIN profiles with subwavelength features, integrated with silicon waveguides, is experimentally demonstrated. Benefitting from the index distribution and beam focusing characteristics of the half Maxwell's fisheye lens, an on-chip beam transforming can be achieved for transverse electric (TE) fundamental mode in two waveguides with different heights and widths. The simulated 1 dB bandwidth can reach 1100nm, which exhibits great prospects in integrated photonic circuits. The measured insertion loss of an on-chip 5.4 μm-length lens is less than 1 dB to connect a 220 nm-height, 8 μm-wide waveguide, and a 60 nm-height, 0.5 μm-wide waveguide in the wavelength range of 1280-1620nm.

Dielectric slot-coupled half-Maxwell fisheye lens as octave-bandwidth beam expander for terahertz-range applications

We present a paradigm for integrated photonic devices based on broadband slab-confined collimated beams that are launched with half-Maxwell fisheye lenses. Although it is challenging to match to the low-index focus of the lens while maintaining adequate field confinement for a close approximation of a point source, integrated dielectric slot waveguides prove highly suitable, yielding collimators of 90% efficiency and bandwidth greater than one octave. Terahertz technology will benefit from such broadband slab-confined beams to replace free-space optics toward compact, mass-producible systems that do not require manual optical alignment. We present two prototype systems to demonstrate the versatility of this concept, namely, a diagonally set distributed Bragg reflector as a frequency-division diplexer for terahertz communications and an attenuated total reflection-based liquid sensor. Both are enabled by oblique in-slab reflections that are collected at a location other than the originating lens, which is not attainable using ordinary single-mode channel waveguides.

Maxwell Fish-Eye and Half-Maxwell Fish-Eye Based on Graded Photonic Crystals

We report on the design of the Maxwell fish-eye based on graded photonic crystals. It is a radially graded refractive index structure, whose remarkable property is to form perfect images in the sense of geometrical optics. The half-Maxwell fish-eye, which takes advantage of the symmetry of the previous, provides directive emission, which applies, amongst others, to wireless communications. The continuous gradient index is nevertheless difficult to practically realize. We show that graded photonic crystals make it possible to get the radially graded index of the Maxwell fish-eye and that the designed graded photonic crystals exhibit the expected properties. Graded photonic crystals fit the requirements of graded index optics. Moreover, they can be scaled with the wavelength.

An Etched Planar Metasurface Half Maxwell Fish-Eye Lens Antenna

In this communication, a half Maxwell fish-eye (HMFE) lens antenna is designed in the 8–11 GHz band using etched planar metamaterials composed of an array of nonresonant square rings with gap (SRG). The refractive index of the HMFE lens can be flexibly obtained in two different ways: one is to adjust the edge length of the SRG unit cell; the other is to change the gap size and the line width of the SRG unit cell simultaneously. The HMFE lens fed by a nondirective monopole antenna is embedded in a staircase parallel-plate transverse electromagnetic (TEM) waveguide. A prototype of the lens antenna has been fabricated. Simulation and measurement results of both near- and far-field plots demonstrate good focusing properties of the proposed HMFE lens antenna.

Analysis of graphene-based half Maxwell fish-eye lens using effective index method

Graphene is used as an ideal platform for plasmonic optical devices due to its unique electrical and optical characteristics. We proposed a unique effective index method to evaluate a graphene-based half Maxwell fish-eye (HMFE) plasmonic lens on a single flake of graphene, which can focus a surface plasmon polariton plane wave and transform into a spherical wave. Similar to traditional optics, the proposed method can be used to investigate the focusing performance of an HMFE lens versus different parameters, including the incident frequencies, the discrete semiring numbers, the chemical potentials, and the size of the proposed lens. In addition, we use two proposed lenses to build an optical-coupling element, which can transform the beam of a plane wave into a different beam width. The proposed effective index method can be used as a reference in designing plasmonic optical devices with a variable effective index profile on a flake of graphene. The finite element method is employed to realize the numerical simulation, which demonstrates results almost consistent with our design methodology.

A 2-D Multibeam Half Maxwell Fish-Eye Lens Antenna Using High Impedance Surfaces

This letter describes the design and measurement of a planar multibeam half Maxwell fish-eye (HMFE) lens antenna with seven beams in azimuth based on variable high impedance surfaces (HISs). The desired refractive index profile is controlled by using slotted square mushroom metallic cells of different sizes on a grounded dielectric slab. The lens antenna, 6.2λ×3.1λ in lens plane and 0.65 λ total height, is fabricated and characterized in TM mode at 13 GHz for both single- and multiple-beam configurations. The optimized lens for single-beam operation achieves 14.1 dBi measured gain, 67 ° and 12 ° half-power beamwidth for E-plane and H-plane, respectively, and 55.3% impedance bandwidth for -10-dB return loss. This lens can be used to launch multiple beams by implementing an arc array of seven-element short monopoles at the periphery of the lens. The measured overall scan coverage is up to 45 ° with gain drop less than 2.4 dB. Its low profile, light weight (only 136 g), and ease of manufacturing makes it well suited for Local Multipoint Communication Systems (LMCS).

Low-Profile Substrate-Integrated Lens Antenna Using Metamaterials

A low-profile substrate-integrated lens antenna is designed using planar metamaterials for a broadband operation. The lens antenna is based on embedding a Vivaldi antenna source inside a parallel-plate waveguide to illuminate a half Maxwell fish-eye (HMFE) lens operating in X-band. The focusing condition of the lens, requiring a gradient refractive index is achieved through the use of complementary nonresonant metamaterial structures. Numerical simulations are performed to determine the suitable unit cells geometry with respect to the wave launcher inserted into the parallel-plate waveguide. The electric field distribution inside the antenna system has also been explored numerically. Far-field radiation patterns have been measured on a fabricated prototype in an anechoic chamber. It has been shown from both near- and far-field plots that the proposed planar antenna presents good focusing properties.

Tunable gradient refractive index optics using graded plasmonic crystals with semiconductor rods

Using numerical simulations, we demonstrate the feasibility of tunable gradient refractive index optics at terahertz frequencies based on two-dimensional graded plasmonic crystals (GPCs). They consist of semiconductor rods with spatially dependent radii. In the effective medium approximation, the GPCs can be considered as effective media with a graded effective dielectric permittivity. The semiconductor rods have the Drude-type dispersion. By varying free charge carrier concentration in the rods, it is possible to tune their permittivity. In accordance to effective medium theory, the effective permittivity of the whole GPC is changed at the same time. This property is used for the demonstration of a GPC-based lens with a tunable focus, beam deflector with tunable angle of the beam deflection, and the half Maxwell-fisheye and the Luneburg lens as antennas with tunable radiation patterns. In particular, these GPCs can be made invisible to the incoming radiation by equaling the real part of the rods permittivity to the permittivity of air background.

Comparative Design and Analysis of Luneburg and Half Maxwell Fish-Eye Lens Antennas

The design and performances is described of half Maxwell fish-eye (HMFE) and Luneburg lens antennas. Techniques to estimate the gradient index lens weights are first proposed and compared to measurements. Thanks to an analytical method based on spherical modal expansion, the radiation performances of Luneburg and HMFE lens antennas are then quantified and compared. The effects of the shell number, the lens diameter and the air gaps on the lens antenna directivity are investigated. Finally, a minmax optimized 9-shell 60 mm-diameter HMFE lens antenna is characterized at both 77 GHz and 110 GHz for on- and off- axis configurations to show its frequency behavior, focalization and beam scanning properties.

Off-Axis Performances of Half Maxwell Fish-Eye Lens Antennas at 77 GHz

The off-axis performances at 77 GHz of multilayered half Maxwell fish-eye (HMFE) lenses fed by an open-ended waveguide is describes. When moving the feed with respect to (w.r.t.) the lens, it is shown that at least 40deg of scanning can be achieved. Several off-axis configurations of the lens antenna are investigated and compared using a full-wave electromagnetic software. The directivity, far field pattern and scan angle of the lens antenna are reported for a rectilinear and angular off-axis displacement of the feed and also for various distances between the feed and the lens. It is also shown that a three-shell lens is good enough to achieve a wide scan angle. Finally, off-axis measurements done with a three-shell 6.15 lambda0-diameter HMFE lens antenna are compared to computed results to validate the simulations

Design and characterization of half Maxwell fish-eye lens antennas in millimeter waves

This paper presents the performance of multilayered half Maxwell fish-eye (HMFE) lenses fed by aperture-coupled microstrip patch antennas. Manufacturing techniques are reviewed and the shell technique is retained. Many lens configurations are investigated and compared using a full-wave electromagnetic software at 50 GHz. We report the effects of the number of shells, diameter of the lens, and distance between the primary source and the lens on the input impedance, broadside directivity, and aperture efficiency. Thus, we show that aperture efficiencies up to 95% can be obtained for a one-wavelength-diameter lens with only three shells, justifying the interest in such lenses. An analytical optimization method is also proposed and detailed to choose the thickness and permittivity of a three-shell HMFE lens to approach the radial permittivity law as well as possible. Simulations of lens antennas whose shell characteristics are determined by various ways show that the optimized lens is the one that provides the highest broadside directivities. Finally, measurements done with a three-shell four-wavelength diameter lens fed by a 2 times 2 patch antenna array show the validity of these simulations. To our knowledge, this represents the first layered HMFE lens carried out in the millimeter-wave frequency range

Finite-element analysis of complex axisymmetric radiating structures

A finite-element method (FEM) is developed for the analysis of complex axisymmetric radiating structures. The method is based on the electric field formulation with the transverse field expanded in terms of edge-based vector basis functions and the azimuth component expanded using nodal-based scalar basis functions. This mixed representation of the electric field eliminates spurious solutions and permits an easy treatment of boundary conditions on conducting surfaces as well as across material interfaces. The FEM mesh is truncated using a previously developed cylindrical perfectly matched layer (PML). The method has been successfully applied to three radiating structures: a corrugated horn antenna, a spherical Luneburg lens, and a half Maxwell fish eye. Numerical results are presented to show the validity, accuracy, and efficiency of the method.