The Computation of Coaxial Line Step Capacitances

Somlo, P.I.

doi:10.1109/tmtt.1967.1126368

Cited by 107 publications

(28 citation statements)

References 4 publications

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“…Since ideal transmission lines can be used to model TEM transmission lines, the only non-trivial parts to be modelled are where discontinuities or gradual changes between different transmission line sizes or types occur in the physical structure of the combiner. Examples of some of these discontinuities and gradual changes and how they can be modelled can be found in [1,5,8,[14][15][16]. In most cases, some form of equivalent circuit model can be deduced or found in literature.…”

Section: Equivalent Circuit Model Descriptionmentioning

confidence: 99%

“…Note that all circuit element values can be calculated directly from physical dimensions, except for L ind and Z r , which will be implicit parameters in the Space Mapping based optimization. The length l r is simply equal to the length of the ring, and the shunt capacitances, C r1 and C r2 , can be determined by using the information presented in [14]. The values of C r1 and C r2 can in general be different, since the coaxial line sections on either side of the ring can have different inner conductor radii.…”

Section: Peripheral Coaxial Line Transitionmentioning

confidence: 99%

“…The step capacitances C s12 , C s23 , and C s34 can be calculated using the same method as for C r1 and C r2 by using the information in [14]. Note that the transmission length of the tapered section, l t , is not equal to the parameter H t shown in Figs.…”

Section: Complete Circuit Modelmentioning

confidence: 99%

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Design of Axially Symmetric Power Combiners Using Surrogate Based Optimization

Beyers¹,

Villiers²

2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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Abstract. The design and optimization of axially symmetric power combiners usually rely on computationally expensive full-wave simulations. Circuit models are often used to reduce the computational cost, however, full-wave parameter sweeps or optimization are usually still required. Surrogate based optimization utilizing circuit models offers an effective means to reduce the computational cost, since the circuit model can be aligned to the full-wave model, usually resulting in fewer full-wave simulations being required. This paper presents some of the recent advances in using Space Mapping, which is a surrogate based optimization technique, for the design and optimization of axially symmetric power combiners.

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Section: Equivalent Circuit Model Descriptionmentioning

confidence: 99%

Section: Peripheral Coaxial Line Transitionmentioning

confidence: 99%

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Design of Axially Symmetric Power Combiners Using Surrogate Based Optimization

Beyers¹,

Villiers²

2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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“…A discontinuity effect (or fringing effect) may occur in transmission line at the plane of sudden change of geometry and cause reflections, apart from reflections caused by any sudden change of the characteristic impedance of the line (Somlo, 1967). It is very difficult to model, especially at the interface of two different types of transmission lines.…”

Section: Discontinuity Effectmentioning

confidence: 99%

Real-Time Determination Of Soil Type, Water Content, and Density Using Electromagnetics

Drnevich¹,

Lin²,

Qin³

et al. 2001

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Prepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration. AbstractThe primary objective of this study was to explore the potential use of electromagnetic characteristics of soils using the Time Domain Reflectometry (TDR) technique to identify physical properties of soils. Three fundamental studies in this exploration are the frequencydependent electromagnetic properties of soils, the wave propagation in a TDR system, and the inverse analyses of TDR waveforms. The three-phase model for soils was extended to a four-phase model so as to account for the interface effect and hence the soil fineness. The physical parameters of the four-phase model are related to the frequency-dependent dielectric permitivity of the soil through a semiempirical volumetric mixing model. A spectral analysis method was developed to simulate wave propagation in the TDR system in a realistic way. Inverse analysis based on the material model and the wave propagation model was formulated using Bayesian statistics to calibrate the TDR system and to infer material properties from the measured TDR waveform. A TDR probe system was used to measure the dielectric properties of soils in a compaction mold and in the field. An experimental program was carried out to make TDR measurements of 5 different soils with different water contents and densities. The result of the inverse analysis matched the TDR waveform very well and determined the dielectric spectrum of soils. With the ability to measure the dielectric spectrum of soils, the apparent dielectric constant at a particular frequency can be calculated. Results showed that the apparent dielectric constant at 1 GHz gave much better correlation with soil water content and density than the apparent dielectric constant obtained by measuring the time between reflections from the soil surface and the one from the end of the probe. Additional work was done to assess the effects of temperature of the soil on measured dielectric constant and it showed that temperature effects were relatively small and could be accounted for in a systematic way. The use of the method for soils having large particle sizes was examined and it was found that the method was applicable for particle sizes passing the 19 mm (3/4-in.) sieve as long as the percentage of particles in the larger size range was limited. Finally, the method was examined for use with stabilizing additives for soil. While test results were obtained modified soils, the measured apparent dielectric constant changed with time after compaction whereas the water content by oven drying did not change appreciably. It is conjectured that changes in apparent dielectric constant are sensitive to the hydration caused by these additives. Thus, the use of the TDR method can be a tool to monitor changes in soils containing additives. Detailed study of this phenomenon is continuing. Key WordsTime Domain Reflectometry, electromagnetic wave propagation, soils, gravels, sands, silts, clays, water content, compaction, density, ...

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“…Most simple types of discontinuities such as steps in inner or outer conductors (see e.g., [1][2][3][4]) and wall impedance discontinuities [5][6][7] were analyzed and characterized. For example, in [5] and [6] the scattering of a shielded surface wave in a coaxial waveguide by a wall impedance discontinuity in the inner cylinder has been analyzed.…”

Section: Introductionmentioning

confidence: 99%

Wiener-Hopf Analysis of Finite-Length Impedance Loading in the Outer Conductor of a Coaxial Waveguide

Büyükaksoy¹

2008

PIER B

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Abstract-A new canonical scattering problem consisting of the propagation of the dominant TEM mode at the finite-length impedance discontinuity in the outer conductor of a coaxial waveguide is solved. The contributions from the successive impedance discontinuities are accounted for through the solution of a modified Wiener-Hopf equation. Some graphical results displaying the reflection and transmission characteristic are presented.

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The Computation of Coaxial Line Step Capacitances

Cited by 107 publications

References 4 publications

Design of Axially Symmetric Power Combiners Using Surrogate Based Optimization

Design of Axially Symmetric Power Combiners Using Surrogate Based Optimization

Real-Time Determination Of Soil Type, Water Content, and Density Using Electromagnetics

Wiener-Hopf Analysis of Finite-Length Impedance Loading in the Outer Conductor of a Coaxial Waveguide

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