scholarly journals Tunable Two-Layer Dual-Band Metamaterial with Negative Modulus

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3229
Author(s):  
Limei Hao ◽  
Meiling Men ◽  
Yazhe Wang ◽  
Jiayu Ji ◽  
Xiaole Yan ◽  
...  
Keyword(s):  
Mass Density ◽  
Hollow Spheres ◽  
Volume Ratio ◽  
Blue Shift ◽  
Relative Volume ◽  
Hole Diameter ◽  
Dual Band ◽  
Resonant Frequencies ◽  
In Series ◽  
Simulation Results

A tunable dual-band acoustic metamaterial (AM) with nested two-layer split hollow spheres (TLSHSs) is presented here, which was achieved by adjusting the hole diameter and the ratio of the two layers’ volumes. This work comprises theoretical and numerical studies. Based on sound-force analogy (SFA), TLSHSs can be considered equivalent to a model of two spring oscillators in series. The equations of two resonant frequencies were derived, which precisely provided the relation between two resonant frequencies and the hole diameter as well as the ratio of the two layers’ volumes. The analytical formulas and simulation results by the finite element method (FEM) showed that there were two resonant frequencies for the TLSHSs, and their dynamic modulus became negative near the resonant frequencies. As the the diameter of two holes increased, both of the resonant frequencies underwent a blue shift. As the relative volume ratio increased, both of the resonant frequencies underwent a red shift. The calculation and simulation results were in good agreement. This kind of precisely controllable dual-band AM with negative modulus can easily be coupled to other structures with negative mass density, thereby achieving a double-negative AM in an expected frequency range.

scholarly journals DUAL-BAND RECONFIGURABLE MIMO ANTENNA FOR WIRELESS APPLICATIONS

2021 ◽  
Vol 25 (3) ◽  
pp. 1-9
Author(s):  
Abdullah A. Jabber ◽  
◽  
Raad H. Thaher ◽  
Keyword(s):  
Coupling Effect ◽  
Mimo System ◽  
Dual Band ◽  
Reconfigurable Antenna ◽  
Pin Diode ◽  
Wireless Devices ◽  
Resonant Frequencies ◽  
Mimo Antenna ◽  
Wireless Applications ◽  
Simulation Results

This article presents design and simulation of a new compact four-element dual-band MIMO frequency reconfigurable antenna that can be reconfigured for WiMAX and LTE applications. The antenna includes four elements at the same FR4 substrate with an optimized overall size of 65x65x1.6 mm3 and an optimized partial GND plane of 30x11.125 mm2. The reconfiguration rate is between 2.41 and 3.99 GHz that can cover the WiMAX and LTE wireless devices by applying just one RF (PIN) switch to change the operating frequency. The antenna operates on the two states of the PIN diode under its two states ON and OFF with (2.7 GHz, and 2.8 GHz) resonant frequencies respectively. The proposed antenna produces acceptable simulation results for the MIMO system by achieving gain from (3-7.2) dBi, less than -14.5 dB coupling effect, less than 0.28 envelope correlation coefficient, and diversity gain range from 8.4-10.

Dual-Band Bandpass Filter Optimized for High Q-Factor

2021 ◽  
Vol 36 (4) ◽  
pp. 398-410
Author(s):  
Walid Fahmy ◽  
Asmaa Farahat ◽  
Khalid Hussein ◽  
Abd-El-Hadi Ammar
Keyword(s):  
Quality Factor ◽  
Bandpass Filter ◽  
High Quality Factor ◽  
Dual Band ◽  
Optimized Design ◽  
Hybrid Architecture ◽  
Quality Factors ◽  
High Quality ◽  
Resonant Frequencies ◽  
Simulation Results

High quality factor bandpass filters based on a number of cascaded resonators of dual-resonance mechanism are proposed in the present paper. Each resonator is constructed as two overlapped coplanar waveguide (CPW) resonant structures. The cascaded resonators mediate microwave coupling between two isolated corner-shaped CPW feeders only at the resonant frequencies leading to a bandpass filter of high quality factor. The two resonant frequencies and the separation between them can be fine-tuned by the dimensions of the structure. The effects of the dimensional parameters of the resonator and the feeding CPW regions on the resonant frequencies and the performance of the bandpass filter are investigated. The effect of the loss tangent of the dielectric substrate material on the quality factors at the two resonant frequencies is studied. Three prototypes of the proposed filter are fabricated and experimentally studied for more understanding of the underlying physical principles of operation and for verifying some of the simulation results. The experimental results show good agreement when compared with the corresponding simulation results. It is shown that, at low enough absolute temperature, the proposed structure can operate as superconducting microwave resonator when made from the appropriate materials. Also, it is shown that an optimized design of the proposed bandpass filter, based on superconducting CPWR structure, can achieve quality factors high enough to form a quantum data bus for hybrid architecture of quantum information systems.

scholarly journals Simultaneous Multi-Bragg Peak Coherent X-ray Diffraction Imaging

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 312
Author(s):  
Florian Lauraux ◽  
Stéphane Labat ◽  
Sarah Yehya ◽  
Marie-Ingrid Richard ◽  
Steven J. Leake ◽  
...  
Keyword(s):  
Bragg Reflection ◽  
Volume Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Substrate ◽  
In Series ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Lattice Planes ◽  
Oriented Parallel

The simultaneous measurement of two Bragg reflections by Bragg coherent X-ray diffraction is demonstrated on a twinned Au crystal, which was prepared by the solid-state dewetting of a 30 nm thin gold film on a sapphire substrate. The crystal was oriented on a goniometer so that two lattice planes fulfill the Bragg condition at the same time. The Au 111 and Au 200 Bragg peaks were measured simultaneously by scanning the energy of the incident X-ray beam and recording the diffraction patterns with two two-dimensional detectors. While the former Bragg reflection is not sensitive to the twin boundary, which is oriented parallel to the crystal–substrate interface, the latter reflection is only sensitive to one part of the crystal. The volume ratio between the two parts of the twinned crystal is about 1:9, which is also confirmed by Laue microdiffraction of the same crystal. The parallel measurement of multiple Bragg reflections is essential for future in situ and operando studies, which are so far limited to either a single Bragg reflection or several in series, to facilitate the precise monitoring of both the strain field and defects during the application of external stimuli.

Numerical Analysis on the Extruded Volume and Length Ratios of Backward Tube to Forward Rod in Combined Extrusion Processes

2006 ◽  
Vol 519-521 ◽  
pp. 919-924 ◽  
Author(s):  
B.S. Ham ◽  
J.H. Ok ◽  
Jung Min Seo ◽  
Beong Bok Hwang ◽  
K.H. Min ◽  
...  
Keyword(s):  
Process Parameters ◽  
Material Flow ◽  
Volume Ratio ◽  
Forward Direction ◽  
Extrusion Process ◽  
Forming Load ◽  
Tube Extrusion ◽  
Corner Radius ◽  
Combined Operation ◽  
Simulation Results

This paper is concerned with forward rod extrusion combined simultaneously with backward tube extrusion process in both steady and transient states. The analysis has been conducted in numerical manner by employing a rigid-plastic finite element method. AA 2024 aluminum alloy was selected as a model material for analysis. Among many process parameters, major design factors chosen for analysis include frictional condition, thickness of tube in backward direction, punch corner radius, and die corner radius. The main goal of this study is to investigate the material flow characteristics in combined extrusion process, i.e. forward rod extrusion combined simultaneously with backward tube extrusion process. Simulation results have been summarized in term of relationships between process parameters and extruded length and volume ratios, and between process parameters and force requirements, respectively. The extruded length ratio is defined as the ratio of tube length extruded in backward direction to rod length extruded in forward direction, and the volume ratio as that of extruded volume in backward direction to that in forward direction, respectively. It has been revealed from the simulation results that material flow into both backward and forward directions are mostly influenced by the backward tube thickness, and other process parameters such as die corner radius etc. have little influence on the volume ratio particularly in steady state of combined extrusion process. The pressure distributions along the tool-workpiece interface have been also analyzed such that the pressure exerted on die is not so significant in this particular process such as combined operation process. Comparisons between multi-stage forming process in sequence operation and one stage combined operation have been also made in terms of forming load and pressure exerted on die. The simulation results shows that the combined extrusion process has the greatest advantage of lower forming load comparing to that in sequence operation.

A compact dual-band D-CRLH-based antenna with self-isolation functionality

2021 ◽  
pp. 1-10
Author(s):  
Mahmoud A. Abdalla ◽  
Mohamed El Atrash ◽  
Ahmed A. Abdel Aziz ◽  
Mohamed I. Abdelnaser
Keyword(s):  
Patch Antenna ◽  
Planar Waveguide ◽  
Dual Band ◽  
Resonant Frequencies ◽  
Left Handed ◽  
Directional Radiation ◽  
Full Wave ◽  
Compact Size ◽  
Filtering Function ◽  
Filter Structures

Abstract This paper presents a compact dual-band filtering antenna without extra employing of filter structures. The antenna is designed using a planar dual-composite right/left-handed (D-CRLH) transmission line unit cell, where the filtering function is achieved through current cancellation between the D-CRLH resonators. The antenna is designed to function at 3.0 and 5.1 GHz, which can serve different WLAN applications. The antenna is a co-planar waveguide fed with a very compact size of only 30 × 16 mm2. Compared to the conventional patch antenna, the antenna size is only 17% at 3.0 GHz and 31% at 5.1 GHz. Despite the small size, the antenna preserves a good omni-directional radiation pattern at the two resonant frequencies with a measured realized gain of 2 and 2.7 dB, respectively. At the stopband in-between the two resonant bands, the reflection coefficient is almost 0 dB at 4.25 GHz and complete non-radiation is proved with a −11 dB measured realized gain. The different antenna filtering functions are verified by full-wave simulation and measurements.

scholarly journals Dual band Stepped Impedance Interdigital Microstrip Filter for LTE Bands

2019 ◽  
Vol 4 (7) ◽  
pp. 28-30
Author(s):  
William Johnson ◽  
Cavin Roger Nunes ◽  
Savio Sebastian Dias ◽  
Siddhi Suresh Parab ◽  
Varsha Shantaram Hatkar
Keyword(s):  
Insertion Loss ◽  
Bandpass Filter ◽  
Dual Band ◽  
Band Pass Filter ◽  
Coupled Resonators ◽  
Microstrip Filter ◽  
Resonant Frequencies ◽  
Pass Filter ◽  
Band Pass ◽  
Low Insertion Loss

In this paper, a dual band microstrip bandpass filter has been proposed utilizing three edge coupled resonators, interdigital stubs and DGS technique. To enhance the coupling degree, two interdigital coupled feed lines are employed in this filter. The suppressing cell consists of stepped impedance ladder type resonators, which provides a wide stopband. The proposed suppressing cell has clear advantages like low insertion loss in the passband and suitable roll off. The frequency response of the filter looks like a standard dual band band-pass filter. The filter exhibits a dual passband with resonant frequencies at 2.2GHz and 3.45GHz covers LTE1 and LTE22 bands.

Design of a high-gain dual-band antipodal Vivaldi antenna array for 5G communications

2021 ◽  
pp. 1-9
Author(s):  
Sumit Kumar ◽  
Amruta S. Dixit
Keyword(s):  
Frequency Spectrum ◽  
Impedance Matching ◽  
High Gain ◽  
Dual Band ◽  
Dual Frequency ◽  
Band Frequency ◽  
Dielectric Lens ◽  
Bottom Side ◽  
Simulation Results ◽  
Vivaldi Antenna

Abstract This paper presents a dual-band 1 × 4 antipodal Vivaldi antenna (AVA) array with high gain to operate over a dual-frequency band that covers the 5G frequency spectrum. The gain is enhanced by employing a dielectric lens (DL). The AVA array consists of four radiating patch elements, corrugations, DL, and array feeding network on the top side. The bottom side contains four radiating patches which are the mirror images of top radiating patches. The designed AVA contains 1 × 4 array antenna elements with a DL that is operating in the ranges of 24.59–24.98 and 27.06–29 GHz. The dimensions of the designed antenna are 97.2 mm × 71.2 mm × 0.8 mm. For the improvement in gain and impedance matching at the dual-band frequency, corrugation and feeding network techniques are used. The gain obtained is about 8–12 dBi. AVA array is tested after fabrication and the measured results are reliable with the simulation results.

Novel dual-band multistrip monopole antenna with defected ground structure for WLAN/IMT/BLUETOOTH/WIMAX applications

2013 ◽  
Vol 6 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Jaswinder Kaur ◽  
Rajesh Khanna ◽  
Machavaram Kartikeyan
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Design Procedure ◽  
Monopole Antenna ◽  
Dual Band ◽  
Impedance Bandwidth ◽  
Area Network ◽  
Defected Ground Structure ◽  
Ground Structure ◽  
Simulation Results

In the present work, a novel multistrip monopole antenna fed by a cross-shaped stripline comprising one vertical and two horizontal strips has been proposed for wireless local area network (WLAN)/Industrial, Scientific, and Medical band (ISM)/International Mobile Telecommunication (IMT)/BLUETOOTH/Worldwide Interoperability for Microwave Access (WiMAX) applications. The designed antenna has a small overall size of 20 × 30 mm2. The goal of this paper is to use defected ground structure (DGS) in the proposed antenna design to achieve dual-band operation with appreciable impedance bandwidth at the two operating modes satisfying several communication standards simultaneously. The antenna was simulated using Computer Simulation Technology Microwave Studio (CST MWS) V9 based on the finite integration technique (FIT) with perfect boundary approximation. Finally, the proposed antenna was fabricated and some performance parameters were measured to validate against simulation results. The design procedure, parametric analysis, simulation results along with measurements for this multistrip monopole antenna using DGS operating simultaneously at WLAN (2.4/5.8 GHz), IMT (2.35 GHz), BLUETOOTH (2.45 GHz), and WiMAX (5.5 GHz) are presented.

Effect of Geometric Parameters in the Upsetting and Extruding Riveting Process on the Quality of Riveted Joints

2015 ◽  
Vol 651-653 ◽  
pp. 1439-1444 ◽  
Author(s):  
Wei Jia Li ◽  
Lian Fa Yang
Keyword(s):  
Hole Diameter ◽  
Geometric Parameters ◽  
Hole Wall ◽  
Riveted Joints ◽  
Riveting Process ◽  
Simulation Results

Upsetting and extruding riveting is a new joining method, which is mainly used to join castings. In order to investigate the effect of geometric dimensions of punch and upper sheet hole diameter on the quality of joints, models with different geometric parameters were simulated via ABAQUS. According to the simulation results, the riveting process could be divided into five stages. Besides, diameter difference on rivet tail and interference value on upper sheet hole wall were selected as indicators to evaluate quality of joints. And a group of parameters is obtained for a better quality of joints. Finally, the simulation results were validated through experiments.

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