scholarly journals A Broadband Ultrathin Nonlinear Switching Metamaterial

2017 ◽  
Vol 6 (2) ◽  
pp. 64
Author(s):  
E. Zarnousheh Farahani ◽  
S. Jarchi ◽  
A. Keshtkar
Keyword(s):  
Incident Wave ◽  
Optimization Method ◽  
Resonant Mode ◽  
Unit Cell ◽  
Incident Power ◽  
Full Wave ◽  
Effective Impedance ◽  
Nonlinear Simulations ◽  
Switching Property ◽  
Transmission And Reflection

In this paper, an ultrathin planar nonlinear metamaterial slab is designed and simulated. Nonlinearity is provided through placing diodes in each metamaterial unit cell. The diodes are auto-biased and activated by an incident wave. The proposed structure represents a broadband switching property between two transmission and reflection states depending on the intensity of the incident wave. High permittivity values are presented creating a near zero effective impedance at low power states, around the second resonant mode of the structure unit cell; as the result, the incident wave is reflected. Increasing the incident power to the level which can activate the loaded diodes in the structure results in elimination of the resonance and consequently a drop in the permittivity values near the permeability one as well as a switch to the transmission state. A full wave as well as a nonlinear simulations are performed. An optimization method based on weed colonization is applied to the unit cell of the metamaterial slab to achieve the maximum switching bandwidth. The structure represents a 24% switching bandwidth of a 10 dB reduction in the reflection coefficient.

scholarly journals Characterization of Tiled Architecture for C-Band 1-Bit Beam-Steering Transmitarray

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1259
Author(s):  
Dmitry Kozlov ◽  
Irina Munina ◽  
Pavel Turalchuk ◽  
Vitalii Kirillov ◽  
Alexey Shitvov ◽  
...  
Keyword(s):  
Communication Systems ◽  
Beam Steering ◽  
Unit Cell ◽  
Electromagnetic Simulations ◽  
Fifth Generation ◽  
Full Wave ◽  
Array Architecture ◽  
Modulation Pattern ◽  
Good Agreement

A new implementation of a beam-steering transmitarray is proposed based on the tiled array architecture. Each pixel of the transmitarray is manufactured as a standalone unit which can be hard-wired for specific transmission characteristics. A set of complementary units, providing reciprocal phase-shifts, can be assembled in a prescribed spatial phase-modulation pattern to perform beam steering and beam forming in a broad spatial range. A compact circuit model of the tiled unit cell is proposed and characterized with full-wave electromagnetic simulations. Waveguide measurements of a prototype unit cell have been carried out. A design example of a tiled 10 × 10-element 1-bit beam-steering transmitarray is presented and its performance benchmarked against the conventional single-panel, i.e., unibody, counterpart. Prototypes of the tiled and single-panel C-band transmitarrays have been fabricated and tested, demonstrating their close performance, good agreement with simulations and a weak effect of fabrication tolerances. The proposed transmitarray antenna configuration has great potential for fifth-generation (5G) communication systems.

Compact Dual-Passband Three-Dimensional FSS with Good Angular Stability and Both-Side Fast Roll-Off Characteristics

2021 ◽  
Vol 36 (6) ◽  
pp. 664-669
Author(s):  
Zhengyong Yu ◽  
Baozhu Li ◽  
Shenggao Ding ◽  
Wanchun Tang
Keyword(s):  
Electromagnetic Waves ◽  
Electromagnetic Coupling ◽  
Three Dimensional ◽  
Frequency Selective Surface ◽  
Resonant Mode ◽  
Unit Cell ◽  
Angular Stability ◽  
Propagation Path ◽  
Annular Slot ◽  
Parallel Plate Waveguide

A compact dual-passband three-dimensional (3D) frequency selective surface (FSS) is proposed based on multiple square coaxial waveguides (SCWs), which exhibits good angular stability and both-side fast roll-off characteristics. The unit cell of the proposed 3D FSS is composed of one parallel plate waveguide (PPW) propagation path and two SCW propagation paths. By etching a centered annular slot, each SCW path forms two identical short SCWs. Each short SCW inherently generates one square slot resonance. In each SCW path, on the account of electromagnetic coupling between two square slot resonators provided by two short SCWs, the square slot resonant mode will split into even-/odd-resonant modes. Accordingly, each SCW path can provide a flat second-order passband with two transmission poles. Due to the reflection and out of phase of electromagnetic waves, four transmission zeros located at both sides of the passbands are introduced for high frequency selectivity, realizing both-side fast roll-off performances. In order to explain the operating principle, the electric-field distributions at transmission-zero/pole frequencies are investigated. Finally, an FSS prototype is fabricated and measured, and the results exhibit good angular stability for both TE and TM polarizations under incident angles from 0° to 60°. In addition, the proposed 3D FSS has a compact unit cell.

scholarly journals Frequency Diversity Array for Near-Field Focusing

Electronics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 958
Author(s):  
Xu Han ◽  
Shuai Ding ◽  
Yongmao Huang ◽  
Yuliang Zhou ◽  
Huan Tang ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Numerical Methods ◽  
Numerical Optimization ◽  
Near Field ◽  
Optimization Method ◽  
Frequency Diversity ◽  
Initial Amplitude ◽  
Full Wave ◽  
Circular Arrays ◽  
Working Frequency

In this study, a numerical optimization method is proposed to achieve the near-field focusing of square arrays and circular arrays. This method introduced the frequency diversity array (FDA) approach to change the initial amplitude and working frequency. By adjusting the working state of each antenna, the field distribution on any plane can be artificially controlled. To analyze the FDA, a mathematical model for the FDA has been built and the model has been optimized by a numerical algorithm. The results of two different kinds of arrays are verified by numerical methods and full-wave simulation.

scholarly journals Fast Hierarchical Optimization Method for High Speed Channel Design Using Channel Operating Margin

2020 ◽  
Author(s):  
Bo Pu
Keyword(s):  
High Speed ◽  
Impedance Matching ◽  
Optimization Method ◽  
Design Flow ◽  
Hierarchical Optimization ◽  
Physical Parameters ◽  
Channel Design ◽  
Horizontal Structure ◽  
Full Wave ◽  
Operating Margin

This paper proposes a design flow for channel design by a fast hierarchical optimization method based on Channel Operating Margin (COM). Unlike the common design of experiment (DOE), the method performs the design by a hierarchical flow in the level of electrical characteristic while not the usual horizontal structure of physical parameters. It significantly reduces the number of huge samples used in DOE, and thus is able to offer a fast estimation approach for channel in the early design period. In each stage of the vertical flow, the electrical properties of component are extracted by 2.5D or 3D full wave simulator, and thus ensure the accuracy of the channel design. Design strategy for the most crucial discontinuity, Via, to achieve an impedance matching is addressed. Package effect on the COM is also discussed as a reference for adjusting the 3dB criterion of COM in the future.

scholarly journals Fast Hierarchical Optimization Method for High Speed Channel Design Using Channel Operating Margin

2020 ◽  
Author(s):  
Bo Pu
Keyword(s):  
High Speed ◽  
Impedance Matching ◽  
Optimization Method ◽  
Design Flow ◽  
Hierarchical Optimization ◽  
Physical Parameters ◽  
Channel Design ◽  
Horizontal Structure ◽  
Full Wave ◽  
Operating Margin

This paper proposes a design flow for channel design by a fast hierarchical optimization method based on Channel Operating Margin (COM). Unlike the common design of experiment (DOE), the method performs the design by a hierarchical flow in the level of electrical characteristic while not the usual horizontal structure of physical parameters. It significantly reduces the number of huge samples used in DOE, and thus is able to offer a fast estimation approach for channel in the early design period. In each stage of the vertical flow, the electrical properties of component are extracted by 2.5D or 3D full wave simulator, and thus ensure the accuracy of the channel design. Design strategy for the most crucial discontinuity, Via, to achieve an impedance matching is addressed. Package effect on the COM is also discussed as a reference for adjusting the 3dB criterion of COM in the future.

Lattice Structure Design for Additive Manufacturing: Unit Cell Topology Optimization

2019 ◽  
Author(s):  
Bradley Hanks ◽  
Mary Frecker
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Lattice Structure ◽  
Optimization Method ◽  
Structure Design ◽  
Unit Cell ◽  
Lattice Structures ◽  
Design For Additive Manufacturing ◽  
Structure Topology

Abstract Additive manufacturing is a developing technology that enhances design freedom at multiple length scales, from the macroscale, or bulk geometry, to the mesoscale, such as lattice structures, and even down to tailored microstructure. At the mesoscale, lattice structures are often used to replace solid sections of material and are typically patterned after generic topologies. The mechanical properties and performance of generic unit cell topologies are being explored by many researchers but there is a lack of development of custom lattice structures, optimized for their application, with considerations for design for additive manufacturing. This work proposes a ground structure topology optimization method for systematic unit cell optimization. Two case studies are presented to demonstrate the approach. Case Study 1 results in a range of unit cell designs that transition from maximum thermal conductivity to minimization of compliance. Case Study 2 shows the opportunity for constitutive matching of the bulk lattice properties to a target constitutive matrix. Future work will include validation of unit cell modeling, testing of optimized solutions, and further development of the approach through expansion to 3D and refinement of objective, penalty, and constraint functions.

scholarly journals Plasmon resonances management of meta-mirror for combining radar cross section (RCS) reduction and specular reflection with frequency selectivity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ali Pesarakloo ◽  
Alireza Oruji
Keyword(s):  
Cross Section ◽  
Incident Wave ◽  
Specular Reflection ◽  
Radar Cross Section ◽  
Unit Cell ◽  
Frequency Selectivity ◽  
Polarization Conversion ◽  
Plasmon Resonances ◽  
Specific Frequency

AbstractIn this paper using Plasmon Resonances Management (PRM), a bi-functional meta-mirror is proposed in which, the meta-mirror can obtain two opposite properties in two different frequency ranges. In this method, an anisotropic unit cell with polarization conversion property is modified to have two plasmon resonances in both symmetric and anti-symmetric planes in a specific frequency. This allows the unit cell to have the property of unchanged polarization in that frequency. The meta-mirror is composed of this modified unit cell and its mirror as a chessboard arrangement and the incident wave on the meta-mirror is reflected as in-phase in that specific frequency i.e. specular reflection, while as out-of-phase in other frequencies i.e. RCS reduction. The designed meta-mirror in this paper demonstrates the RCS reduction in two side-bands from 4 to 9 GHz and 10.8 to 14.8 GHz while behaving as a specular reflection in the frequency around 10 GHz.

Topology Optimization of Headstock of Heavy Machine Tool

2011 ◽  
Vol 305 ◽  
pp. 442-445
Author(s):  
Feng Lan Cheng ◽  
Feng He Wu
Keyword(s):  
Sensitivity Analysis ◽  
Topology Optimization ◽  
Machine Tool ◽  
Cross Section ◽  
Structure Optimization ◽  
Optimization Method ◽  
Unit Cell ◽  
Optimization Process ◽  
Topological Parameters ◽  
Heavy Machine

The problem of topology optimization of large spindle box of heavy machine was studied. Based on ICM topology optimization, the parameters topology optimization were changed by sensitivity analysis and the sensitivity parameters were normalized; the topological parameters were modified and removed which judgment based on the sensitivity of the cross-section unit cell in the progress of optimization. Example shown that the integrated optimization method made the structure optimization more intuitive, not only avoided effectively the occurrence of the load strange in the optimization process, but accelerated the convergence speed.

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