LOOP ANTENNA WITH A SEMICONDUCTOR ELEMENT

2021 ◽  
Author(s):  
П.А. ТИТОВЕЦ ◽  
А.И. САТТАРОВА ◽  
А.А. ПИЩЕРКОВ ◽  
Н.С. БЕКУШЕВ
Keyword(s):  
Laser Radiation ◽  
Reflection Coefficient ◽  
Copper Foil ◽  
Loop Antenna ◽  
Laser Source ◽  
Reflection Coefficients ◽  
Building Element ◽  
External Contour ◽  
In Series ◽  
Loop Antennas

Представлены результаты исследований рамочной антенны, в которой подстроечным элементом является фоторезистор, управляемый лазерным излучением. Показано, что использование фоторезистора как элемента внешнего контура рамочной антенны, включенного последовательно, позволяет изменять согласование рамочной антенны с помощью внешнего лазерного источника. Представлены результаты исследований характеристик коэффициента передачи рамочных антенн, состоящих из медной фольги на диэлектрической основе и полупроводникового элемента. Установлено, что при изменении интенсивности лазерного излучения, падающего на полупроводниковый элемент-фоторезистор, изменяется коэффициент отражения рамочной антенны. В диапазоне от 10 МГц до 18ГГц получены зависимости коэффициентов отражения (Su)рамочных антенн с полупроводниковым элементом. Проведено сравнение рамочной антенны и рамочной антенны с фоторезистором. The results of an experiment with a loop antenna, in which the building element is a photoresistor controlled by laser radiation, are presented. It is shown that the use of a photoresistor as an element of the external contour of a loop antenna connected in series makes it possible to change the matching of the loop antenna due to an external laser source. The results of studies of the characteristics of the transmission coefficient of loop antennas consisting of a dielectric copper foil and a semiconductor element are presented. It was found that when the intensity of the laser radiation incident on the semiconductor element-photoresistor changes, the reflection coefficient of the frame antenna changes. In the range of 10 MHz-18 GHz, the dependences of the reflection coefficients (S11) of loop antennas with a semiconductor element are obtained. A comparison is made between a loop antenna and a loop antenna with a photoresistor.

scholarly journals Plasma semiconductor antenna

2021 ◽  
Vol 2103 (1) ◽  
pp. 012187
Author(s):  
A S Brusentsev ◽  
N N Bogachev ◽  
S G Dogaev ◽  
S Yu Kazantsev ◽  
A I Sattarova ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Laser Plasma ◽  
Return Loss ◽  
Satellite Navigation ◽  
Loop Antenna ◽  
Laser Source ◽  
Scattering Parameter ◽  
Loop Antennas ◽  
And Control ◽  
Plasma Control

Abstract The purposes of this work was to study the possibility of using photoconductive semiconductor antenna based on Ge or GaAs for receiving information signals in the frequency communications and satellite navigation bands and to study a scattering parameter S11 – a return loss (a reflection coefficient) of configurable loop antennas with laser-plasma control based on semiconductor photoresistor. It is shown that the addition of semiconductor photoresistor element in the loop antenna makes it possible to significantly expand its functionality and control its characteristics using an external laser source.

scholarly journals Experimental study of the influence of laser radiation power on the reflection coefficient of germanium and silicon at a wavelength of 355 nm

2021 ◽  
Vol 2103 (1) ◽  
pp. 012154
Author(s):  
T V Malinskiy ◽  
V Yu Zheleznov ◽  
V E Rogalin ◽  
I A Kaplunov
Keyword(s):  
Experimental Study ◽  
Laser Radiation ◽  
Energy Density ◽  
Reflection Coefficient ◽  
Radiation Power ◽  
Optical Breakdown ◽  
Reflection Coefficients ◽  
Laser Radiation Power ◽  
Complex Character ◽  
Analytical Expressions

Abstract The dependences of the reflection coefficients at a wavelength of λ = 355 nm for germanium and silicon single crystals on the energy density of impacting laser radiation in the range 0.01 - 0.1 J/cm2 have been measured. Analytical expressions were obtained. It is assumed, that they are also valid in the range 0.1 - 1.0 J/cm2. With a further increase in the energy density, the dependence should acquire a more complex character due to the resulting optical breakdown.

scholarly journals NIR Laser Photobiomodulation Induces Neuroprotection in an In Vitro Model of Cerebral Hypoxia/Ischemia

2021 ◽  
Author(s):  
Elisabetta Gerace ◽  
Francesca Cialdai ◽  
Elettra Sereni ◽  
Daniele Lana ◽  
Daniele Nosi ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Cerebral Ischemia ◽  
Molecular Mechanisms ◽  
Hippocampal Slices ◽  
Treatment Protocol ◽  
Synaptic Activity ◽  
Laser Source ◽  
Therapeutic Window ◽  
Hypoxia Ischemia ◽  
Nir Laser

AbstractBrain photobiomodulation (PBM) is an innovative treatment for a variety of neurological conditions, including cerebral ischemia. However, the capability of PBM for ischemic stroke needs to be further explored and its mechanisms of action remain currently unclear. The aim of the present research was to identify a treatment protocol capable of inducing neuroprotection and to investigate the molecular mechanisms activated by a dual-wavelength near infrared (NIR) laser source in an organotypic hippocampal slice model of hypoxia/ischemia. Hippocampal slices were exposed to oxygen and glucose deprivation (OGD) for 30 min followed by NIR laser light (fluence 3.71, 7.42, or 14.84 J/cm2; wavelengths 808 nm and 905 nm) delivered immediately or 30 min or 60 min after OGD, in order to establish a therapeutic window. Neuronal injury was assessed by propidium iodide fluorescence 24 h later. Our results show that NIR laser irradiation attenuates OGD neurotoxicity once applied immediately or 30 min after OGD. Western blot analysis of proteins involved in neuroinflammation (iNOS, COX-2, NFkB subunit p65, and Bcl-2) and in glutamatergic-mediated synaptic activity (vGluT1, EAAT2, GluN1, and PSD95) showed that the protein modifications induced by OGD were reverted by NIR laser application. Moreover, CA1 confocal microscopy revealed that the profound morphological changes induced by OGD were reverted by NIR laser radiation. In conclusion, NIR laser radiation attenuates OGD neurotoxicity in organotypic hippocampal slices through attenuation of inflammatory mechanisms. These findings shed light on molecular definition of NIR neuroprotective mechanisms, thus underlining the potential benefit of this technique for the treatment of cerebral ischemia.

scholarly journals A Compact Four-Port Coplanar Antenna Based on an Excitation Switching Reconfigurable Mechanism for Cognitive Radio Applications

2019 ◽  
Vol 9 (15) ◽  
pp. 3157 ◽  
Author(s):  
O ◽  
Jin ◽  
Choi
Keyword(s):  
Cognitive Radio ◽  
High Frequency ◽  
Coplanar Waveguide ◽  
Low Frequency ◽  
Loop Antenna ◽  
Ultra Wideband ◽  
Frequency Range ◽  
Uwb Antenna ◽  
High Isolation ◽  
Loop Antennas

In this paper, we propose a compact four-port coplanar antenna for cognitive radio applications. The proposed antenna consists of a coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna and three inner rectangular loop antennas. The dimensions of the proposed antenna are 42 mm × 50 mm × 0.8 mm. The UWB antenna is used for spectrum sensing and fully covers the UWB spectrum of 3.1–10.6 GHz. The three loop antennas cover the UWB frequency band partially for communication purposes. The first loop antenna for the low frequency range operates from 2.96 GHz to 5.38 GHz. The second loop antenna is in charge of the mid band from 5.31 GHz to 8.62 GHz. The third antenna operates from 8.48 GHz to 11.02 GHz, which is the high-frequency range. A high isolation level (greater than 17.3 dB) is realized among the UWB antenna and three loop antennas without applying any additional decoupling structures. The realized gains of the UWB antenna and three loop antennas are greater than 2.7 dBi and 1.38 dBi, respectively.

Measurement of osmotic reflection coefficient for small molecules in cat hindlimbs

1989 ◽  
Vol 256 (1) ◽  
pp. H282-H290 ◽  
Author(s):  
M. B. Wolf ◽  
P. D. Watson
Keyword(s):  
Skeletal Muscle ◽  
Reflection Coefficient ◽  
Small Molecules ◽  
Osmotic Pressure ◽  
Maximum Rate ◽  
Reflection Coefficients ◽  
Flow Rates ◽  
Perfusate Flow ◽  
Arterial Inflow ◽  
Osmotic Reflection Coefficient

Capillary osmotic reflection coefficients (sigma) for NaCl, urea, sucrose, and raffinose were measured in the isolated, perfused cat hindlimb using the osmotic transient technique. sigma were determined from the ratio of the maximum rate of transcapillary absorption [delta Jv(max)] to the increase in the osmotic pressure (25-35 mosmol/kg H2O) in the arterial inflow (delta pi a) produced by adding one of the molecules to an albumin-electrolyte perfusate containing isoproterenol (greater than 10(-7) M). delta Jv (max) was determined from organ weight and delta pi a from perfusate osmolalities. For each molecule, the delta Jv(max)/delta pi a ratio increased monotonically with perfusate flow rates (Q) to Q greater than 100 ml.min-1.100 g-1. This ratio was independent of the size of the delta pi a. Apparent sigma values were calculated by dividing these ratios by the capillary hydraulic capacity determined in other studies. At low Q, apparent sigma was comparable to the approximately 0.1 values found by others in skeletal muscle. At the highest Q, apparent sigma for these molecules were at least 0.5. These data are consistent with at least 50% of transcapillary water flow moving through a water-exclusive pathway.

Protein osmotic pressure gradients and microvascular reflection coefficients

1997 ◽  
Vol 273 (2) ◽  
pp. H997-H1002 ◽  
Author(s):  
R. E. Drake ◽  
S. Dhother ◽  
R. A. Teague ◽  
J. C. Gabel
Keyword(s):  
Reflection Coefficient ◽  
Pressure Gradient ◽  
Osmotic Pressure ◽  
Reflection Coefficients ◽  
Pressure Gradients ◽  
Fluid Filtration ◽  
The Mean ◽  
Osmotic Reflection Coefficient ◽  
New Equation ◽  
Osmotic Pressure Gradient

Microvascular membranes are heteroporous, so the mean osmotic reflection coefficient for a microvascular membrane (sigma d) is a function of the reflection coefficient for each pore. Investigators have derived equations for sigma d based on the assumption that the protein osmotic pressure gradient across the membrane (delta II) does not vary from pore to pore. However, for most microvascular membranes, delta II probably does vary from pore to pore. In this study, we derived a new equation for sigma d. According to our equation, pore-to-pore differences in delta II increase the effect of small pores and decrease the effect of large pores on the overall membrane osmotic reflection coefficient. Thus sigma d for a heteroporous membrane may be much higher than previously derived equations indicate. Furthermore, pore-to-pore delta II differences increase the effect of plasma protein osmotic pressure to oppose microvascular fluid filtration.

Boundary conditions for the numerical solution of wave propagation problems

Geophysics ◽  
1978 ◽  
Vol 43 (6) ◽  
pp. 1099-1110 ◽  
Author(s):  
Albert C. Reynolds
Keyword(s):  
Wave Propagation ◽  
Reflection Coefficient ◽  
Finite Difference ◽  
Boundary Conditions ◽  
Numerical Solution ◽  
Neumann Boundary ◽  
Synthetic Seismograms ◽  
Neumann Boundary Conditions ◽  
Numerical Calculations ◽  
Reflection Coefficients

Many finite difference models in use for generating synthetic seismograms produce unwanted reflections from the edges of the model due to the use of Dirichlet or Neumann boundary conditions. In this paper we develop boundary conditions which greatly reduce this edge reflection. A reflection coefficient analysis is given which indicates that, for the specified boundary conditions, smaller reflection coefficients than those obtained for Dirichlet or Neumann boundary conditions are obtained. Numerical calculations support this conclusion.

scholarly journals Study of superradiance in the Lambert-W potential barrier

2019 ◽  
Vol 34 (16) ◽  
pp. 1950087 ◽  
Author(s):  
Luis Puente ◽  
Carlos Cocha ◽  
Clara Rojas
Keyword(s):  
Reflection Coefficient ◽  
Potential Barrier ◽  
Gordon Equation ◽  
Reflection Coefficients ◽  
Hyperbolic Tangent ◽  
Step Potential ◽  
Transmission And Reflection Coefficients ◽  
Klein Gordon ◽  
Klein Gordon Equation ◽  
Transmission And Reflection

We present a new potential barrier that presents the phenomenon of superradiance when the reflection coefficient [Formula: see text] is greater than one. We calculated the transmission and reflection coefficients for three different regions. The results are compared with those obtained for the hyperbolic tangent potential barrier and the step potential barrier. We also present the solution of the Klein–Gordon equation with the Lambert-[Formula: see text] potential barrier in terms of the Heun Confluent functions.

Linearized amplitude variation with offset (AVO) inversion with supercritical angles

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. E49-E55 ◽  
Author(s):  
Jonathan E. Downton ◽  
Charles Ursenbach
Keyword(s):  
Reflection Coefficient ◽  
Critical Angle ◽  
Waveform Inversion ◽  
Phase Variation ◽  
Reflection Coefficients ◽  
Amplitude Variation ◽  
Amplitude Variation With Offset ◽  
Zoeppritz Equations ◽  
Avo Inversion ◽  
Angle Data

Contrary to popular belief, a linearized approximation of the Zoeppritz equations may be used to estimate the reflection coefficient for angles of incidence up to and beyond the critical angle. These supercritical reflection coefficients are complex, implying a phase variation with offset in addition to amplitude variation with offset (AVO). This linearized approximation is then used as the basis for an AVO waveform inversion. By incorporating this new approximation, wider offset and angle data may be incorporated in the AVO inversion, helping to stabilize the problem and leading to more accurate estimates of reflectivity, including density reflectivity.

Quantitative synthesis of head and foreleg arterial pulses in the dog

1965 ◽  
Vol 208 (5) ◽  
pp. 968-983 ◽  
Author(s):  
John W. Remington
Keyword(s):  
Pulse Height ◽  
Pressure Change ◽  
Wave Impedance ◽  
Reflection Coefficients ◽  
Reflected Waves ◽  
Basic Assumptions ◽  
Junction Points ◽  
Quantitative Synthesis ◽  
In Series ◽  
Arterial Pulses

The carotid and the subclavian arterial-systems were treated as though composed of a series of homogeneous distensible tubes joined in series or in parallel. With minor corrections, the contour of the aortic arch pulse was taken as that of a single transient incident wave entering the proximal end of these systems. Pulse height changes were localized to the junctions between coupled tubes of dissimilar wave impedance values. The amount of pressure change at these junctions was calculated by comparing arterial pulses recorded from various sites in these systems with the aortic pulse. An attempt was made to keep a strict accounting of all reflected waves arising either from the junction points or from peripheral drainage beds. The pulse constructions provided evidence for appreciable junctional positive reflections which alter the contour of the peripheral pulses. Because returning reflected waves from these sites were reflected negatively at each junction, their amplitude on entering the aorta was relatively small. The good-to-excellent reconstructions of the actual pulse contours suggest that the method of analysis used has promise, and that the basic assumptions on which the calculation of reflection coefficients was based did not impose errors of critical importance.

Sign in / Sign up

Export Citation Format

Share Document