scholarly journals Theoretical and Numerical Analysis of Active Switching for Narrow-Band Thermal Emission with Graphene Ribbon Metasurface

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6738
Author(s):  
Kyohei Yada ◽  
Takashi Shimojo ◽  
Hideyuki Okada ◽  
Atsushi Sakurai
Keyword(s):  
Quality Factor ◽  
Electromagnetic Waves ◽  
Thermal Emission ◽  
Impedance Matching ◽  
Equivalent Circuit Model ◽  
Optical Devices ◽  
Field Analysis ◽  
Graphene Ribbon ◽  
Artificial Structure ◽  
Theoretical And Numerical Analysis

Components smaller than the wavelength of electromagnetic waves are called meta-atoms. Thermal emission can be controlled by an artificial structure in which these meta-atoms are arranged on the surface. This artificial structure is called a metasurface, and its optical properties are determined by the materials and shapes of the meta-atoms. However, optical devices may require active control of thermal emission. In the present study, we theoretically and numerically analyze a wavelength-selective emitter using a graphene ribbon metasurface. The graphene ribbon metasurface consists of a graphene ribbon array, potassium bromide thin film, and silver substrate. The geometric parameters of the graphene metasurface are determined based on an equivalent circuit model that agrees well with the results of the electromagnetic field analysis (rigorous coupled-wave analysis). The proposed emitter causes impedance matching depending on the conductivity of the graphene ribbon in a very narrow wavelength range. The conductivity of graphene can be actively controlled by the gate voltage. Therefore, the proposed emitters may realize near-perfect emission with a high quality factor and active controllable switching for various wavelengths. In addition, the quality factor can be changed by adjusting the electron mobility of graphene. The proposed emitter can be used for optical devices such as thermophotovoltaic systems and biosensing.

Reduced Cross-Polarization Patch Antenna with Optimized Impedance Matching Using a Complimentary Split Ring Resonator and Slots as Defected Ground Structure

2021 ◽  
Vol 36 (6) ◽  
pp. 718-725
Author(s):  
Narayanasamy RajeshKumar ◽  
Palani Sathya ◽  
Sharul Rahim ◽  
Akaa Eteng
Keyword(s):  
Patch Antenna ◽  
Ring Resonator ◽  
Impedance Matching ◽  
Equivalent Circuit Model ◽  
Split Ring Resonator ◽  
Cross Polarization ◽  
Defected Ground Structure ◽  
Ground Structure ◽  
Split Ring ◽  
Surface Current Density

An innovative method is proposed to improve the cross-polarization performance and impedance matching of a microstrip antenna by integrating a complimentary split ring resonator and slots as a defected ground structure. An equivalent circuit model (ECM) enables the design take into consideration the mutual coupling between the antenna patch and the Defected Ground Structure. The input impedance and surface current density analysis confirms that the integration of a CSRR within a rectangular microstrip patch antenna leads to uniform comparative cross-polarization level below 40 dB in the H-plane, over an angular range of ± 50°. Introducing parallel slots, as well, leads to a reduction of spurious antenna radiation, thereby improving the impedance matching. Measurements conducted on a fabricated prototype are consistent with simulation results. The proposed antenna has a peak gain of 4.16 dB at 2.6 GHz resonating frequency, and hence is good candidate for broadband service applications.

ON-CHIP INDUCTORS OPTIMIZATION FOR ULTRA WIDE BAND LOW NOISE AMPLIFIERS

2011 ◽  
Vol 20 (07) ◽  
pp. 1231-1242 ◽  
Author(s):  
J. DEL PINO ◽  
SUNIL L. KHEMCHANDANI ◽  
ROBERTO DÍAZ-ORTEGA ◽  
R. PULIDO ◽  
H. GARCÍA-VÁZQUEZ
Keyword(s):  
Quality Factor ◽  
Noise Figure ◽  
Impedance Matching ◽  
Broad Band ◽  
Wide Band ◽  
Design Guidelines ◽  
Low Noise ◽  
Low Noise Amplifiers ◽  
Integrated Inductor ◽  
On Chip

In this work, the influence of the inductor quality factor in wide band low noise amplifiers has been studied. Electromagnetic simulations have been used to model the integrated inductor broad band response. The influence of the quality factor on LNA performance of the inductors that compound the impedance matching networks, inductive degeneration and broadband load has been studied, obtaining design guidelines for optimizing the amplifier gain flatness. Using this guidelines, an LNA with wideband input matching, shunt-peaking load, and an output buffer was designed. Using Austria Mikro Systems BiCMOS 0.35 m process, a prototype has been fabricated achieving the following measured specifications: maximum gain of 12.5 dB at 3.4 GHz with a -3 dB bandwidth of 1.7–5.3 GHz, noise figure from 4.3 to 5.2 dB, and unity gain at 9.4 GHz.

Extraordinary Coherent Thermal Emission From SiC Due to Coupled Resonant Cavities

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Nir Dahan ◽  
Avi Niv ◽  
Gabriel Biener ◽  
Yuri Gorodetski ◽  
Vladimir Kleiner ◽  
...  
Keyword(s):  
Quality Factor ◽  
Coherence Length ◽  
Thermal Emission ◽  
Spatial Coherence ◽  
Optical Filters ◽  
High Quality Factor ◽  
Experimental Results ◽  
Thermal Source ◽  
High Quality ◽  
Resonant Cavities

In high temperature and vacuum applications, when heat transfer is predominantly by radiation, the material’s surface texture is of substantial importance. Several micro- and nanostructure designs have been proposed to enhance a material’s emissivity and its radiative coherence, as control of thermal emission is of crucial concern in the design of infrared sources, optical filters, and sensing devices. In this research, an extraordinary coherent thermal emission from an anisotropic microstructure is experimentally and theoretically presented. The enhanced coherency is due to coherent coupling between resonant cavities obtained by surface standing waves, wherein each cavity supports a localized field that is attributed to coupled surface phonon polaritons. We show that it is possible to obtain a polarized quasimonochromatic thermal source from a SiC microstructure with a high quality factor of 600 at the resonant frequency of the cavity and a spatial coherence length of 716 wavelengths, which corresponds to an angular divergence of 1.4mrad. In the experimental results, we measured a quality factor of 200 and a spatial coherence length of 143 wavelengths. We attribute the deviation in the experimental results to imperfections in the fabrication of the high quality factor cavities.

Equivalent circuit model of a rectangular RF driven hydrogen ion source for impedance matching network design

2018 ◽  
Vol 136 ◽  
pp. 1422-1427
Author(s):  
Sung-Ryul Huh ◽  
Min Park ◽  
Bong-Ki Jung ◽  
Doo-Hee Chang ◽  
Tae-Seong Kim ◽  
...  
Keyword(s):  
Network Design ◽  
Equivalent Circuit ◽  
Impedance Matching ◽  
Equivalent Circuit Model ◽  
Ion Source ◽  
Circuit Model ◽  
Hydrogen Ion ◽  
Matching Network

scholarly journals Broadband Radar Absorbing Structures with a Practical Approach from Design to Fabrication

2020 ◽  
Vol 20 (4) ◽  
pp. 254-261
Author(s):  
Won-Ho Choi ◽  
Woon-Hyung Song ◽  
Won-Jun Lee
Keyword(s):  
Multiple Scattering ◽  
Electromagnetic Waves ◽  
Point Of View ◽  
Design Concept ◽  
Field Analysis ◽  
Design Values ◽  
Absorption Performance ◽  
Incident Waves ◽  
Lossy Materials ◽  
Space Measurement

In this study, a novel broadband radar absorbing volume structure (RAVS) is proposed and demonstrated with a practical point of view from design to fabrication. The proposed RAVS uses a design concept of repeatedly stacked carbon nanotube (CNT) composites and foam cores of the same thickness to improve the applicability to real structures while maintaining absorption performance. The repeatedly stacked CNT composites, which act as electrically lossy materials, result in the multiple scattering of incident electromagnetic waves trapped inside the structure. The trapped incident waves then lose their energy by multiple scattering. Based on this design concept, the RAVS designed through field analysis and parametric study achieved a −10 dB absorption performance from 4 GHz to 16 GHz. With reference to the design values, RAVS was fabricated for verification, and the absorption performance was measured using a free space measurement system. The measurement result showed excellent absorption performance that satisfied −10 dB from 5.8 GHz or less to 14 GHz.

scholarly journals Development of Broadband Underwater Radio Communication for Application in Unmanned Underwater Vehicles

2020 ◽  
Vol 8 (5) ◽  
pp. 370
Author(s):  
Igor Smolyaninov ◽  
Quirino Balzano ◽  
Dendy Young
Keyword(s):  
Electromagnetic Waves ◽  
Impedance Matching ◽  
Underwater Vehicles ◽  
Skin Depth ◽  
Radio Communication ◽  
Propagation Length ◽  
Unmanned Underwater Vehicles ◽  
Communication Technique ◽  
Surface Electromagnetic Waves ◽  
Small Form Factor

This paper presents several novel designs of small form factor underwater radio antennas operating in the 2 MHz, 50 MHz and 2.4 GHz bands. These antennas efficiently excite surface electromagnetic waves (SEW) which propagate along the surface of seawater. The antenna operation is made possible due to implementation of an impedance matching enclosure, which is filled with de-ionized water. Enhanced coupling to surface electromagnetic waves is enabled by the enhancement of the electromagnetic field at the antenna apex. These features allow us to make antenna dimensions considerably smaller compared to typical free space designs. They also considerably improve coupling of electromagnetic energy to the surrounding seawater. Since SEW propagation length is considerably larger than the skin depth in seawater, this technique is useful for underwater broadband wireless communication. We conclude that the developed broadband underwater radio communication technique will be useful in networking of unmanned underwater vehicles.

Design of a transmission-line metamaterial with a negative index of refraction at S-Band / Concepção de um metamaterial de linha de transmissão com um índice negativo de refracção na banda S

2021 ◽  
Vol 7 (7) ◽  
pp. 73312-73322
Author(s):  
Lucas Douglas Ribeiro ◽  
Arthur Henrique de Lima Ferreira ◽  
Juscelino Júnior De Oliveira ◽  
Rose Mary de Souza Batalha
Keyword(s):  
Transmission Line ◽  
Transverse Electric ◽  
Negative Refractive Index ◽  
Impedance Matching ◽  
Equivalent Circuit Model ◽  
Index Of Refraction ◽  
Two Dimensional ◽  
Dispersion Characteristics ◽  
Negative Index Of Refraction ◽  
Line Network

A metamaterial based on a two-dimensional transmission-line network loaded with inductors and capacitors enabling to achieve negative-refractive-index (NRI) is developed. The dispersion characteristics are calculated by their equivalent circuit model and an operating frequency of 2.95 GHz in which there is impedance matching with free space is chosen in the S-Band. This NRI metamaterial supports transverse electric (TE) waves, thus it can be used in applications such as lensing. 

Variability Analysis of Pi Network Impedance Matching

2013 ◽  
Vol 291-294 ◽  
pp. 2527-2531
Author(s):  
Jian Wen Tan ◽  
Si Jian Deng ◽  
Fang Wei Ye ◽  
De Ping Zeng
Keyword(s):  
Reflection Coefficient ◽  
Quality Factor ◽  
Large Deviation ◽  
Design Method ◽  
Impedance Matching ◽  
Perfect Match ◽  
Small Variation ◽  
Load Impedance ◽  
Harmonic Rejection ◽  
Impedance Variation

Harmonic rejection ability and reflection coefficient are the most important factors in the design of impedance matching network. However, stability of impedance matching should be taken into account in applications existing load impedance variation and component deviation due to tolerance and process variation. This paper investigates variability of Pi network impedance matching analytically. The relationships between resulting reflection coefficient with component deviation and load impedance variation are theoretically derived on the basis of Q-based design method. The deviation from perfect match due to component deviation is proportional to quality factor. Higher quality factor probably means poorer quality in terms of variability. The resulting reflection coefficient caused by load impedance variation increases rapidly when the load reflection coefficient is larger than 0.66. A small variation in the load impedance will cause a large deviation from perfect match when the impedance difference between load and source is quite large.

scholarly journals Scattering, absorption, and thermal emission by large cometary dust particles: Synoptic numerical solution

2019 ◽  
Vol 631 ◽  
pp. A164 ◽  
Author(s):  
Johannes Markkanen ◽  
Jessica Agarwal
Keyword(s):  
Light Scattering ◽  
Numerical Solution ◽  
Electromagnetic Waves ◽  
Random Media ◽  
Thermal Emission ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Conductive Heat ◽  
Interplanetary Dust Particles ◽  
Cometary Dust

Context. Remote light scattering and thermal infrared observations provide clues about the physical properties of cometary and interplanetary dust particles. Identifying these properties will lead to a better understanding of the formation and evolution of the Solar System. Aims. We present a numerical solution for the radiative and conductive heat transport in a random particulate medium enclosed by an arbitrarily shaped surface. The method will be applied to study thermal properties of cometary dust particles. Methods. The recently introduced incoherent Monte Carlo radiative transfer method developed for scattering, absorption, and propagation of electromagnetic waves in dense discrete random media is extended for radiative heat transfer and thermal emission. The solution is coupled with the conductive Fourier transport equation that is solved with the finite-element method. Results. The proposed method allows the synoptic analysis of light scattering and thermal emission by large cometary dust particles consisting of submicrometer-sized grains. In particular, we show that these particles can sustain significant temperature gradients resulting in the superheating factor phase function observed for the coma of comet 67P/Churyumov–Gerasimenko.

Optimization Design of Microwave Absorbing Composites Containing Activated Carbon Fibers

2010 ◽  
Vol 160-162 ◽  
pp. 24-28 ◽  
Author(s):  
Tian Chun Zou ◽  
Zhen Yu Feng
Keyword(s):  
Activated Carbon ◽  
Carbon Fibers ◽  
Electromagnetic Waves ◽  
Optimization Design ◽  
Design Method ◽  
Average Length ◽  
Impedance Matching ◽  
Activated Carbon Fibers ◽  
Microwave Absorbing Materials ◽  
Microwave Absorbing

Microwave absorbing materials (MAMs) is a key component for weapon systems such as aircrafts, warships, and missiles to achieve the stealth performance by absorbing electromagnetic waves incident on. In this work, activated carbon fibers (ACFs) with average length of 1-3mm were prepared, and ACFs dielectric properties were investigated. The results show that ACFs have the frequency response effect, which is helpful for broadening the absorbing bands. According to ACF permittivity, the optimal design is carried out for four-layer microwave absorbing composites with thickness of 4mm based on the impedance matching design method. Following the optimization results the four-layer absorbing material was prepared, and it obtains a reflection loss below -10dB over 8GHz and the minimum value reaches -39.3dB in 2-18GHz.

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