Material-based high-impedance surfaces for infrared photonic technologies

2022 ◽  
Vol 1 ◽  
pp. 1-4
Author(s):  
Iñigo Liberal ◽  
◽  
José Manuel Pérez-Escudero ◽  
Keyword(s):  
Basic Research ◽  
Large Area ◽  
Magnetic Conductor ◽  
Doped Semiconductors ◽  
Impedance Boundary ◽  
High Impedance ◽  
Radar Systems ◽  
Thermal Emitters ◽  
Push Forward ◽  
Infrared Frequencies

Metamaterial high-impedance surfaces (HISs) are characterized by a boundary condition close to that of aperfect magnetic conductor (PMC). This property has enabled a variety of antenna systems such as low-profileantennas, electromagnetic absorbers and anti-radar systems. Here, we push forward the concept of material-basedhigh-impedance surfaces (MatHISs), where a high-impedance boundary is directly obtained from the materialproperties of doped semiconductors and polar dielectrics at infrared frequencies. Technological advantages ofMatHISs such as fabrication simplicity, large-area deployment and integrability into conformal devices suggestmultiple applications for infrared photonic technologies, including dynamical thermal emitters, optoelectronic devicesand basic research on atomically-thin materials.

Wave conversions from earthquakes and a new velocity model for the South Carolina coastal plain

1987 ◽  
Vol 77 (6) ◽  
pp. 2143-2151
Author(s):  
Susan Rhea
Keyword(s):  
Surface Layer ◽  
South Carolina ◽  
Coastal Plain ◽  
Velocity Structure ◽  
Velocity Model ◽  
Seismogenic Fault ◽  
Impedance Boundary ◽  
High Impedance ◽  
Hypocentral Parameters ◽  
Converted Phases

Abstract Phase conversions from P to SV and from SV to P occur at a high impedance boundary near the surface in Charleston, South Carolina. Four arrivals (P, converted P, converted S, and S) are observed on three-component records of earthquakes in this area. Using arrival-time differences between paired arrivals of direct and converted phases, a shallow surface layer Vp/Vs ratio of 2.9 was determined. Applying the Wadati method to travel times derived at the base of the surface layer yields a Vp/Vs ratio in deeper layers of 1.73. Relocating earthquakes using this more appropriate velocity structure for direct and converted shear waves alters hypocentral parameters such that epicenters diverge and depths converge. It is inferred that these relocated earthquakes are not exclusively associated with a single seismogenic fault.

scholarly journals PERANCANGAN DAN FABRIKASI PENYERAP GELOMBANG ELEKTROMAGNETIK PATCH SEGI ENAM BERBASIS SURFACE TEXTURED

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Levy Olivia Nur ◽  
Achmad Munir ◽  
Sugihartono Sugihartono ◽  
Adit Kurniawan
Keyword(s):  
Magnetic Conductor ◽  
Impédance Surface ◽  
Impedance Surface ◽  
Artificial Magnetic Conductor ◽  
High Impedance ◽  
High Impedance Surface

Teknologi surface textured yang merupakan salah satu teknik untuk pengembangan penyerap gelombang elektromagnetik telah mengalami perkembangan yang cukup pesat dalam dekade terakhir ini. Pada aplikasi penyerap, teknologi ini mampu mengurangi ketebalan material sehingga memungkinkan realisasi material yang lebih tipis. Secara prinsip, teknik ini menggunakan lapisan AMC (artificial magnetic conductor) yang mempunyai high impedance surface. Untuk mendapatkan tingkat penyerapan yang tinggi yang dapat bekerja pada frekuensi penyerapan yang diinginkan, metal patch dari penyerap tersebut dibuat dengan bentuk tertentu. Pada penelitian ini, dilakukan investigasi bentuk patch segi enam sama sisi yang dicetak di atas substrat dielektrik FR4 Epoxy dengan ketebalan 3,2 mm. Ukuran substrat dielektrik sel satuan yang didapatkan untuk bentuk segi enam 30 mm � 26,5 mm, sedangkan lebar sisi patch yang diperoleh 14 mm. Selanjutnya untuk mendapatkan tingkat penyerapan yang baik dilakukan penambahan elemen resistif pada patch. Nilai resistor yang perlu ditambahkan pada patch saat perancangan adalah 514 : dengan tingkat penyerapan pada frekuensi kerjanya sebesar 47 dB. Pengukuran telah dilakukan dengan menggunakan alat bantu PPW simulator. Kemudian dilakukan proses pemisahan karakteristik penyerap dari alat pengukurannya. Penambahan resistor sebesar 487 : memberikan pengaruh karakteristik penyerapan hingga 34 dB lebih baik sekitar 7 dB pada frekuensi resonansi 2,78 GHz bila dibandingkan dengan pengukuran tanpa R. Kata Kunci: AMC, penyerap, karakterisasi, patch, surface textured, sel satuan

EBSP: A powerful tool in studying recrystallization of metals

1994 ◽  
Vol 52 ◽  
pp. 610-611
Author(s):  
T. Furu ◽  
O. Lohne ◽  
Ø. Sødahl ◽  
E. Nes
Keyword(s):  
Texture Evolution ◽  
Basic Research ◽  
Recrystallization Process ◽  
Large Area ◽  
X Ray ◽  
Local Texture ◽  
Subgrain Growth ◽  
Short Processing Time ◽  
Back Scattering ◽  
Established Technique

The Electron Back Scattering Pattern Technique (EBSP), for measurements of crystal orientations is now a well established technique for microtexlure detennination. The application of the technique to material problems has increased quite substantially the last years, both in basic research and in more industry related problems. When studying the recrystallization process in detail a relatively large area of a specimen has to be investigated to obtain good statistical results. With a resolution of the order of 0.5-1 μm and a short processing time the EBSPtechnique has shown to be advantageous compared to TEM on one side and X-ray and neutron diffraction on the other. By the EBSP-technique we are able to follow the local texture evolution during transformation and are at the same time able to analyse changes in the untransfonncd matrix (i.e. subgrain growth etc.).It is well accepted that the formation of recrystallization nuclei is a highly heterogeneous process.

Emerging research in plant photosynthesis

2020 ◽  
Vol 4 (2) ◽  
pp. 137-150 ◽  
Author(s):  
Thomas D. Sharkey
Keyword(s):  
Green Light ◽  
Basic Research ◽  
Light Energy ◽  
Good News ◽  
Regulatory Mechanisms ◽  
Large Area ◽  
Protective Mechanisms ◽  
Light Levels ◽  
Plant Photosynthesis ◽  
To Come

Photosynthesis involves capturing light energy and, most often, converting it to chemical energy stored as reduced carbon. It is the source of food, fuel, and fiber and there is a resurgent interest in basic research on photosynthesis. Plants make excellent use of visible light energy; leaves are ideally suited to optimize light use by having a large area per amount of material invested and also having leaf angles to optimize light utilization. It is thought that plants do not use green light but in fact they use green light better than blue light under some conditions. Leaves also have mechanisms to protect against excess light and how these work in a stochastic light environment is currently a very active area of current research. The speed at which photosynthesis can begin when leaves are first exposed to light and the speed of induction of protective mechanisms, as well as the speed at which protective mechanisms dissipate when light levels decline, have recently been explored. Research is also focused on reducing wasteful processes such as photorespiration, when oxygen instead of carbon dioxide is used. Some success has been reported in altering the path of carbon in photorespiration but on closer inspection there appears to be unforeseen effects contributing to the good news. The stoichiometry of interaction of light reactions with carbon metabolism is rigid and the time constants vary tremendously presenting large challenges to regulatory mechanisms. Regulatory mechanisms will be the topic of photosynthesis research for some time to come.

scholarly journals Surface magneto plasmons and their applications in the infrared frequencies

Nanophotonics ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 383-396 ◽  
Author(s):  
Bin Hu ◽  
Ying Zhang ◽  
Qi Jie Wang
Keyword(s):  
Magnetic Field ◽  
Plane Surface ◽  
Broad Band ◽  
Device Fabrication ◽  
Lower Plasma ◽  
Doped Semiconductors ◽  
Beam Splitters ◽  
Fundamental Investigation ◽  
Nonreciprocal Effect ◽  
Infrared Frequencies

Abstract Due to their promising properties, surface magneto plasmons have attracted great interests in the field of plasmonics recently. Apart from flexible modulation of the plasmonic properties by an external magnetic field, surface magneto plasmons also promise nonreciprocal effect and multi-bands of propagation, which can be applied into the design of integrated plasmonic devices for biosensing and telecommunication applications. In the visible frequencies, because it demands extremely strong magnetic fields for the manipulation of metallic plasmonic materials, nano-devices consisting of metals and magnetic materials based on surface magneto plasmon are difficult to be realized due to the challenges in device fabrication and high losses. In the infrared frequencies, highly-doped semiconductors can replace metals, owning to the lower incident wave frequencies and lower plasma frequencies. The required magnetic field is also low, which makes the tunable devices based on surface magneto plasmons more practically to be realized. Furthermore, a promising 2D material-graphene shows great potential in infrared magnetic plasmonics. In this paper, we review the magneto plasmonics in the infrared frequencies with a focus on device designs and applications. We investigate surface magneto plasmons propagating in different structures, including plane surface structures and slot waveguides. Based on the fundamental investigation and theoretical studies, we illustrate various magneto plasmonic micro/nano devices in the infrared, such as tunable waveguides, filters, and beam-splitters. Novel plasmonic devices such as one-way waveguides and broad-band waveguides are also introduced.

Low profile dual‐band antenna loaded with artificial magnetic conductor for indoor radar systems

2015 ◽  
Vol 9 (2) ◽  
pp. 184-190 ◽  
Author(s):  
Sen Yan ◽  
Ping Jack Soh ◽  
Marco Mercuri ◽  
Dominique M.M.‐P. Schreurs ◽  
Guy A.E. Vandenbosch
Keyword(s):  
Dual Band ◽  
Magnetic Conductor ◽  
Artificial Magnetic Conductor ◽  
Dual Band Antenna ◽  
Radar Systems ◽  
Low Profile

scholarly journals Corporate Feed, Compact 2X2 Array Antenna With Enhanced Radiation Characteristics using Metamaterial Structure

2019 ◽  
Vol 8 (4) ◽  
pp. 2807-2812
Keyword(s):  
Mutual Coupling ◽  
Transverse Electric ◽  
Side Lobe ◽  
Transverse Magnetic ◽  
Array Antenna ◽  
Magnetic Conductor ◽  
Radiation Characteristics ◽  
High Impedance ◽  
Unit Cells ◽  
High Impedance Surface

In current study, mushroom type metamaterial substrate is designed to operate at ISM band and is embedded in 2X2 array as a ground. Unique properties of mushroom type metamaterial substrate like as high impedance surface (HIS) helped in design of low aperture antenna, Artificial magnetic conductor (AMC) helps in enhancing the radiation characteristics and Forbidden band gap (FBG) helps in suppressing transverse electric (TE) and transverse magnetic (TM) wave propagation hence point of mutual coupling and side lobe levels are reduced. So, 2X2 array antenna with corporate feed resonating at 2.5GHz is embedded by array of mushroom type metamaterial unit cells is designed in HFSS and obtained results are compared with 2X2 array resonating at 2.5GHz on conventional conducting ground results. An enhancement in impedance band width of 2.47%, gain of 2.91dB and with lowered side lobe reduction of 3.74dB.

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