Impedance matching with an adjustable segmented transmission line

Cui, Qian; Brey, Wallace S.

doi:10.1016/j.jmr.2009.04.005

Cited by 18 publications

(9 citation statements)

References 19 publications

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“…This brings the problem of impedance matching. When the impedance matching is better, the loss of the entire monitoring system is lower, the detection sensitivity is higher, the stability is better and the anti-interference ability is stronger [32]. In this study, the power sweep method is adopted to study the impedance matching problem by scanning the amplitude spectrum of the reflection and transmission.…”

Section: B Detection Principlementioning

confidence: 99%

A Dual Parameter Synchronous Monitoring System of Brain Edema Based on the Reflection and Transmission Characteristics of Two-Port Test Network

Yang

et al. 2019

IEEE Access

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As a common secondary disease, edema after traumatic brain injury (TBI) can increase brain volume, resulting in elevated intracranial pressure (ICP), brain shift, and cerebral hernia, and can eventually lead to death. The real-time continuous monitoring of edema may significantly reduce mortality and disability. In this paper, a dual-parameter synchronous monitoring system of edema based on the reflection and transmission characteristics of the two-port test network was established; 15 rabbits were chosen to perform 24-h reflection phase shift (RPS) and transmission phase shift (TPS) simultaneously monitoring the experiments of brain edema. With the development of brain edema, the variation law of the RPS and TPS was investigated. Combined with the power amplitude spectrum and the principle of the two-port test network, the influence of frequency on the detection sensitivity of RPS and TPS was analyzed in detail, and the optimal detection frequency point was found. After that, the classification of three different degrees of edema is performed by the BP algorithm. In the animal experiment, the RPS showed a continuous increasing trend within time, and it presented the variation of (9.35910 • ± 1.65702 •), (12.60117 • ± 2.30218 •), and (16.33423 • ± 2.11118 •) after 6, 12, and 24 h, respectively. Meanwhile, the TPS showed a continuous downward trend with the variation of (−12.62555 • ± 0.99441 •), (−19.23976 • ± 1.27488 •), and (−27.26285 • ± 2.62291 •) after 6, 12, and 24 h, respectively. The RPS was negatively correlated with the TPS. The RPS and the TPS together as a recognition feature can achieve 100% accurate classification of three different brain edema severities. Based on these results, it can be concluded that the system established in this paper can monitor gradual increases in brain edema severity. Furthermore, neither the RPS nor the TPS can be set as the recognition feature alone to achieve the completely accurate classification, which shows the necessity of presenting two parameters in the monitoring process. INDEX TERMS Brain edema, two-port test network, synchronous monitoring, classification.

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Section: B Detection Principlementioning

confidence: 99%

A Dual Parameter Synchronous Monitoring System of Brain Edema Based on the Reflection and Transmission Characteristics of Two-Port Test Network

Yang

et al. 2019

IEEE Access

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“…On the basis of transmission line theory [8,10,11], the input impedance Z(x) of a line with a length x, loaded with an impedance Z L (see Figure 2-left), depends on the characteristic impedance Z 0 and on the propagation constant γ of the line, determined by (2):…”

Section: Theoretical Proposalmentioning

confidence: 99%

“…The experimental identification of the primary line parameters is essential. Some of these parameters, R and L, can be accurately determined from (7) and (8). Nevertheless, the computation of other primary line parameters can become complex, since they are affected by the properties of the soil, and by the rail-to-rail conductance and capacitance.…”

Section: Theoretical Proposalmentioning

confidence: 99%

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Characterization of railway line impedance based only on short‐circuit measurements

García

Jiménez

Espinosa

et al. 2014

Circuit Theory & Apps

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SUMMARYThis paper presents a new methodology to obtain the line impedance of current railway tracks by using only short-circuit measurements. Open-circuit measurements required by conventional methodologies are discarded, since they cannot be carried out for railway tracks in service (electrically continuous and indefinite length). The mathematical basis of the proposed methodology is based on the transmission line theory but focused on the changes in track length. The proposal has been successfully applied to characterize the impedance of the high-speed railway line at the Spanish AVE Madrid-Valencia (Cuenca) and in the AVE Atocha-Chamartin tunnel (Madrid).

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“…In recent years, studies of the interaction of waves with inhomogeneous media have been actively carried out (see [1][2][3][4][5][6][7][8] and references therein). The notion of a "barrier" is frequently used in various fields of science, for which a wave description can be applied, for example, in plasma physics (wave barriers), in solid-state physics (quantum-mechanical barriers), in optics, etc.…”

Section: Introductionmentioning

confidence: 99%

Exactly solvable model for transmission line with artificial dispersion

Shvartsburg

Artekha

2020

Journal of Applied Physics

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The problem of the emergence of wave dispersion due to the heterogeneity of a transmission line (TL) is considered. An exactly solvable model helps to better understand the physical process of a signal passing through a non-uniform section of the line and to compare the exact solution and solutions obtained using various approximate methods. Based on the transition to new variables, the developed approach made it possible to construct exact analytical solutions of telegraph equations with a continuous distribution of parameters, which depend on the coordinate. The flexibility of the discussed model is due to the presence of a number of free parameters, including two geometric factors characterizing the lengths of inhomogeneities in values of the inductance L and of the capacitance C. In the new variables, the spatiotemporal structure of the solutions is described using sine waves and elementary functions, and the dispersion is determined by the formulas of the waveguide type. The dispersive waveguide-like structure characterized by refractive index N and cut-off frequency Ω. The exact expressions for the complex reflection and transmission coefficients are derived. These expressions describe phase shifts for reflected and transmitted waves. The following interesting cases are analyzed: the passage of waves without phase change, the reflectionless passage of waves, and the passage of signals through a sequence of non-uniform sections. The developed mathematical formalism can be useful for the analysis of a wider range of problems.

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Impedance matching with an adjustable segmented transmission line

Cited by 18 publications

References 19 publications

A Dual Parameter Synchronous Monitoring System of Brain Edema Based on the Reflection and Transmission Characteristics of Two-Port Test Network

A Dual Parameter Synchronous Monitoring System of Brain Edema Based on the Reflection and Transmission Characteristics of Two-Port Test Network

Characterization of railway line impedance based only on short‐circuit measurements

Exactly solvable model for transmission line with artificial dispersion

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