scholarly journals Model of Propagation of VLF Beams in the Waveguide Earth-Ionosphere. Principles of Tensor Impedance Method in Multilayered Gyrotropic Waveguides

2019 ◽  
Author(s):  
Yuriy Rapoport ◽  
Vladimir Grimalsky ◽  
Victor Fedun ◽  
Oleksiy Agapitov ◽  
John Bonnell ◽  
...  
Keyword(s):  
Optical Waveguides ◽  
Wide Frequency Range ◽  
Lower Atmosphere ◽  
Impedance Method ◽  
Qualitative Comparison ◽  
Cover Layer ◽  
Lightning Discharges ◽  
Tensor Impedance ◽  
Electromagnetic Beams ◽  
Vlf Waves

Abstract. Modeling propagation of VLF electromagnetic beams in the waveguide earth-ionosphere (WGEI) is of a great importance because variation in the characteristics of these waves is an effective instrument for diagnostics the influences on the ionosphere from above (Sun-Solar Wind-Magnetosphere-Ionosphere), from below (the most powerful meteorological, seismogenic and other sources in the lower atmosphere and lithosphere/Earth, such as hurricanes, earthquakes, tsunamis etc.), from inside the ionosphere (strong thunderstorms and lightning discharges) and even from the far space (such as gamma-flashes, cosmic rays etc.). Thus, VLF became one of the most universal instrument for monitoringthe Space Weather in the direct sense of this term, i.e. the state of the Sun-Earth space and the ionosphere as it is particularly determined by all possible relatively powerful sources, wherever they are placed. This paper is devoted mostly to modelling VLF electromagnetic beam propagation in the WGEI. We present a new tensor impedance method for modelling propagation of electromagnetic beams (TIMEB) in a multi-layered/inhomogeneous waveguide. Suppose that such a waveguide, i.e. WGEI, possesses the gyrotropy and inhomogeneity with a thick cover layer placed above the waveguide. Note a very useful and attractive feature of the proposed TIMEB method: in spite of a large thickness of the waveguide cover layer, the proposed effective impedance approach reflects an impact of such a cover on the electromagnetic (EM) waves, which propagate in the waveguide. This impedance approach can be applied for EM waves/beams in layered gyrotropic/anisotropic active media in very wide frequency range, from VLF to optics. Moreover, this approach can be applied to calculations of EM waves/beams propagation in the media of an artificial origin such as metamaterial microwave or optical waveguides. The results of the modelling the propagation of VLF beams in the WGEI are included. The qualitative comparison between the theory and experimental observation of increasing losses of VLF waves in the WGEI is discussed. The new proposed method and its further development allows the comparison with the results of the future rocket experiment. This method allows to model (i) excitation of the VLF modes in the WGEI and their excitation by the typical VLF sources, such as radio wave transmitters and lightning discharges and (ii) leakage of VLF waves/beams into the upper ionosphere/magnetosphere.

scholarly journals Model of the propagation of very low-frequency beams in the Earth–ionosphere waveguide: principles of the tensor impedance method in multi-layered gyrotropic waveguides

2020 ◽  
Vol 38 (1) ◽  
pp. 207-230
Author(s):  
Yuriy Rapoport ◽  
Vladimir Grimalsky ◽  
Viktor Fedun ◽  
Oleksiy Agapitov ◽  
John Bonnell ◽  
...  
Keyword(s):  
Optical Waveguides ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Signal Propagation ◽  
Wide Frequency Range ◽  
Impedance Method ◽  
Very Low Frequency ◽  
The Earth ◽  
Tensor Impedance ◽  
Electromagnetic Beams

Abstract. The modeling of very low-frequency (VLF) electromagnetic (EM) beam propagation in the Earth–ionosphere waveguide (WGEI) is considered. A new tensor impedance method for modeling the propagation of electromagnetic beams in a multi-layered and inhomogeneous waveguide is presented. The waveguide is assumed to possess the gyrotropy and inhomogeneity with a thick cover layer placed above the waveguide. The influence of geomagnetic field inclination and carrier beam frequency on the characteristics of the polarization transformation in the Earth–ionosphere waveguide is determined. The new method for modeling the propagation of electromagnetic beams allows us to study the (i) propagation of the very low-frequency modes in the Earth–ionosphere waveguide and, in perspective, their excitation by the typical Earth–ionosphere waveguide sources, such as radio wave transmitters and lightning discharges, and (ii) leakage of Earth–ionosphere waveguide waves into the upper ionosphere and magnetosphere. The proposed approach can be applied to the variety of problems related to the analysis of the propagation of electromagnetic waves in layered gyrotropic and anisotropic active media in a wide frequency range, e.g., from the Earth–ionosphere waveguide to the optical waveband, for artificial signal propagation such as metamaterial microwave or optical waveguides.

COHERENCE FUNCTIONS FOR MAGNETOTELLURIC ANALYSIS

Geophysics ◽  
1974 ◽  
Vol 39 (3) ◽  
pp. 312-320 ◽  
Author(s):  
I. K. Reddy ◽  
D. Rankin
Keyword(s):  
Data Analysis ◽  
Linear System ◽  
System Approach ◽  
Partial Coherence ◽  
Impedance Method ◽  
Two Dimensional ◽  
Magnetotelluric Data ◽  
The Earth ◽  
Principal Axes ◽  
Tensor Impedance

A multiinput linear system approach is used to study the magnetotelluric phenomena in the presence of lateral conductivity inhomogeneities in the earth. The three types of coherence functions (ordinary, multiple, and partial) are defined, and their use in magnetotelluric data analysis is illustrated with a field example. Partial coherence functions are used to determine the principal axes in the case of two‐dimensional type inhomogeneities, and as measures of three‐dimensionality in the case of non‐two‐dimensional type structures. The results obtained using coherence functions are compared with those obtained with the conventional tensor impedance method.

scholarly journals Perancangan Filter Bandpass dengan Teknik Penggabungan Filter Lowpass dan Highpass

2018 ◽  
Vol 7 (1) ◽  
pp. 32-38
Author(s):  
Fitri Farida ◽  
Eko Setijadi
Keyword(s):  
Bandpass Filter ◽  
Filter Design ◽  
Short Circuit ◽  
Wide Frequency Range ◽  
Signal Interference ◽  
Impedance Method ◽  
Lowpass Filter ◽  
Microstrip Technology ◽  
Distribution Method ◽  
Highpass Filter

UWB technology started to become an attraction in the field of research since the Federal Communications Commission (FCC) allowing this communication is used for commercial communications at a frequency (3.1 GHz - 10.6 GHz). UWB has a very wide frequency range so that in practice there is often interference due to signal interference. Therefore in UWB system filter design is required to maintain UWB device. In telecommunications, filter is a transmission device that has the function to pass the desired frequency. In this paper designed bandpass filter which is applied for UWB technology. The designed bandpass filter is a combination of a lowpass filter (LPF) and a highpass filter (HPF). The lowpass filter has the characteristic of passing a frequency lower than its cut-off frequency. The highpass filter has the characteristic passing a frequency higher than its cut-off frequency. Considering the characteristics of both filters, the bandpass filter (BPF) is a combination of lowpass and highpass filters. In this research designed lowpass filter in microstrip technology with step-impedance method, that is by combining high impedance microstrip and low impedance microstrip with a certain length. As for designing HPF using the distribution method of short circuit stubs by adding via ground on each stub. The design of this filter uses Roger substrate RT 5880 with dielectric constant er = 2,2 with thickness (h) = 0.508 mm. In this research it can be concluded that bandpass filter can be designed with lowpass and highpass filter incorporation method, although at the merging of highpass and lowpass structures is disturbed by each other, but overall design shows matching bandpass. Keywords—Microstrip, Lowpass Filter, Highpass Filter, Bandpass Filter.

scholarly journals Center Impedance Method for Estimating Complex Modulus with Wide Frequency Range and Large Loss Factors

2021 ◽  
Vol 2021 ◽  
pp. 1-23
Author(s):  
Ryuzo Horiguchi ◽  
Yoshiro Oda ◽  
Keito Sato ◽  
Hiroto Kozuka ◽  
Takao Yamaguchi
Keyword(s):  
Loss Factor ◽  
Wide Frequency Range ◽  
Frequency Function ◽  
Single Frequency ◽  
Impedance Method ◽  
Frequency Range ◽  
Simple Method ◽  
Large Loss ◽  
Mobility Data ◽  
Loss Factors

A simple method for determining viscoelasticity over a wide frequency range using the frequency response function (FRF) mobility obtained by the center impedance method is presented. As user data comprise the FRF between the velocity of the excitation rod and excitation force, it is challenging to separate the signal and noise. Our proposed method is based on the FRF obtained from the analytical solution of the equation of motion of the viscoelastic beam and relationship between the complex wavenumber (real wavenumber and attenuation constant) of flexural wave and viscoelasticity. Furthermore, a large loss factor can be handled over a wide frequency range without using the half-power bandwidth. In this study, actual FRF mobility data containing noise were processed using preprocessing, inverse calculation, and postprocessing. Preprocessing removed low-coherence data, compensates for the effects of instrument gain, and transformed the FRF into its dimensionless equivalent. Then, inverse calculations were used to solve the mobility equation and determine the complex wavenumber. In postprocessing, the complex wavenumber obtained by the inverse calculation was curve fitted using functions with mechanical significance. Consequently, the storage modulus based on the curve-fitted complex wavenumber was a monotonically increasing frequency function. The loss factor had a smooth frequency dependence such that it has the maximum value at a single frequency. The proposed method can be applied to composite materials, where the application of time-temperature superposition is challenging. We utilized the measured FRF mobility data obtained over a duration of several seconds, and this method can also be applied to materials with large loss factors of 1 or more.

scholarly journals Modeling of Equivalent Circuit Analysis of Degraded Electric Double-Layer Capacitors

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 435
Author(s):  
Tomoki Omori ◽  
Masahiro Nakanishi ◽  
Daisuke Tashima
Keyword(s):  
Equivalent Circuit ◽  
Double Layer ◽  
Electric Double Layer ◽  
Wide Frequency Range ◽  
Circuit Analysis ◽  
Impedance Method ◽  
Equivalent Circuit Analysis ◽  
Degradation Diagnosis ◽  
Double Layer Capacitors ◽  
Electric Double Layer Capacitors

The demand for electric double-layer capacitors (EDLCs) has recently increased, especially for regenerative braking systems in electric or hybrid vehicles. However, using EDLCs under high temperature often enhances their degradation. Continuously monitoring EDLC degradation is important to prevent sudden malfunction and rapid drops in efficiency. Therefore, it is useful to diagnose the degradation at a lower frequency than that used in charge/discharge. Unused and degraded EDLCs were analyzed using the alternating current impedance method for measurements over a wide frequency range. Each result had a different spectrum up to 1 kHz. In addition, we show the basic inside condition of EDLCs with equivalent circuit analysis. This paper explores the possibility of degradation diagnosis at a high frequency and the basic physical mechanism.

scholarly journals Electrodynamical Coupling of Earth's Atmosphere and Ionosphere: An Overview

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
A. K. Singh ◽  
Devendraa Siingh ◽  
R. P. Singh ◽  
Sandhya Mishra
Keyword(s):  
Electromagnetic Field ◽  
Electric Circuit ◽  
Lower Atmosphere ◽  
Global Electric Circuit ◽  
Radioactive Elements ◽  
Speed Of Light ◽  
Earth’S Atmosphere ◽  
Lightning Discharges ◽  
Earth's Atmosphere ◽  
Present Understanding

Electrical processes occurring in the atmosphere couple the atmosphere and ionosphere, because both DC and AC effects operate at the speed of light. The electrostatic and electromagnetic field changes in global electric circuit arise from thunderstorm, lightning discharges, and optical emissions in the mesosphere. The precipitation of magnetospheric electrons affects higher latitudes. The radioactive elements emitted during the earthquakes affect electron density and conductivity in the lower atmosphere. In the present paper, we have briefly reviewed our present understanding of how these events play a key role in energy transfer from the lower atmosphere to the ionosphere, which ultimately results in the Earth's atmosphere-ionosphere coupling.

TEM characterization of proton-exchanged LiNbO3 optical waveguides

1986 ◽  
Vol 44 ◽  
pp. 480-481
Author(s):  
W. E. Lee
Keyword(s):  
Refractive Index ◽  
Benzoic Acid ◽  
Optical Waveguides ◽  
Total Internal Reflection ◽  
Index Of Refraction ◽  
Optical Measurements ◽  
Lithium Ions ◽  
Wide Channel ◽  
Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

The Contribution of Phonon-Scattered Electrons to High-Resolution Electron Micrographs of Crystals

1990 ◽  
Vol 48 (1) ◽  
pp. 62-63
Author(s):  
H. Kohl
Keyword(s):  
High Resolution ◽  
Spherical Aberration ◽  
High Resolution Electron Microscopy ◽  
Static Potential ◽  
Qualitative Comparison ◽  
The Past ◽  
Resolution Electron ◽  
High Resolution Images ◽  
High Resolution Electron Micrographs ◽  
Extract Information

High-Resolution Electron Microscopy is able to determine structures of crystals and interfaces with a spatial resolution of somewhat less than 2 Å. As the image is strongly dependent on instrumental parameters, notably the defocus and the spherical aberration, the interpretation of micrographs necessitates a comparison with calculated images. Whereas one has often been content with a qualitative comparison of theory with experiment in the past, one is currently striving for quantitative procedures to extract information from the images [1,2]. For the calculations one starts by assuming a static potential, thus neglecting inelastic scattering processes.We shall confine the discussion to periodic specimens. All electrons, which have only been elastically scattered, are confined to very few directions, the Bragg spots. In-elastically scattered electrons, however, can be found in any direction. Therefore the influence of inelastic processes on the elastically (= Bragg) scattered electrons can be described as an attenuation [3]. For the calculation of high-resolution images this procedure would be correct only if we had an imaging energy filter capable of removing all phonon-scattered electrons. This is not realizable in practice. We are therefore forced to include the contribution of the phonon-scattered electrons.

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