Distortion of Fast Pulses by Non-Tem Effects in Coaxial Cables

Barth, Jon; Richner, John

doi:10.1007/978-1-4899-1394-4_32

Cited by 6 publications

(6 citation statements)

References 2 publications

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“…Therefore, for such nozzle geometry and an interrogation pulse with FWHM value of 0.5 ns, all the frequency components, from 0.913 GHz up to 2 GHz will create TE 11 mode microwaves. This TE 11 mode will be generated at imperfections in the nozzle, and will propagate with a different phase velocity interfering with the TEM mode [5]. It is this interference between the TEM and the TE 11 mode associated with the frequencies higher than fc which will give standing waves evidenced by the ringing effect.…”

Section: Design Methodologymentioning

confidence: 96%

“…Related to the characterization of the interrogation pulse in the frequency domain, as an example, in Fig.3, we present the Fast Fourier Transform of a positive Gaussian pulse V o (t) with a FWHM value of 0.5 ns. Related to the characterization of microwave propagation modes which can be present in coaxial transmission lines of different inner (d) and outer (D) diameters of the conductors, it is well known [5] that beyond the TEM mode with a cut-off frequency of 0 Hz, the next possible mode is TE 11 , which has a frequency cut-off: f c (GHz) =190.85/[(D+d)*Ɛ r 1/2 ], with D and d given in mm [5,6]. This cut-off frequency means that the entire frequency spectrum of the interrogation pulse should be below f c , if we want to preserve a clean TEM mode during pulse propagation along the chain.…”

Section: Design Methodologymentioning

confidence: 99%

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Evidence and effects of higher order modes on the response of guided wave radar-based level sensors

Cobianu

Georgescu

Hughes

et al. 2015

2015 International Semiconductor Conference (CAS)

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In this work we investigate the effects of the pulse duration and geometry of the tank on the time response of the guided wave radar (GWR) level transmitter. By 1 COMSOL ® modelling and simulation we show that for shorter pulses below 0.5ns and larger diameters of the nozzle (above 150 mm) parasitic higher order modes, like TE 11 are generated, affecting the accuracy of level measurement. This TE 11 mode interferes with TEM mode creating standing waves evidenced as "ringing" in the time domain response. The experimental results shown here for pulse duration of 0.27 ns and a diameter of the nozzle of 152 mm are in very good agreement with the model.

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Section: Design Methodologymentioning

confidence: 96%

Section: Design Methodologymentioning

confidence: 99%

Evidence and effects of higher order modes on the response of guided wave radar-based level sensors

Cobianu

Georgescu

Hughes

et al. 2015

2015 International Semiconductor Conference (CAS)

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show abstract

“…We can view the coefficients s m,n as entries in an M × N matrix S M ×N matrix whose row and column indices range over 0 ≤ m < M, 0 ≤ n < N respectively. The DAC performs the mapping s n → p n (t) according to (10) where s n is the n th column of S M ×N . The Fourier transform of p n (t) in (10), which is required to carry out the waveform selection procedure, is…”

Section: A Uwb Pulse Generatormentioning

confidence: 99%

“…We assume in the sample computations done here that the transmission line behaves like an ideal all-pass filter across the measurement band and can be ignored. Distortion of ultra fast pulses in transmission lines has been studied [10] and results have shown that distortions do occur if precautions are not taken.…”

Section: Filtering In the Dacmentioning

confidence: 99%

An ultrawideband signal design with power spectral density constraints

Lewis

Scholtz²

Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.

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Abstract-An UWB signal was designed and generated using a zero order digital to analog converter. An efficiency measure of filling the FCC spectral mask is developed and optimized for various choices of digital-to-analog converter parameters and waveform duration. The proposed optimization technique takes into account filtering effects in the digital-to-analog converter as well as a measured antenna transfer function characteristic.

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“…Above TEM cutoff, higher order modes can contribute to the usable spectrum for short pulse, fast risetime signals if certain effects are ignorable or controlled for [119].…”

Section: Comparative Performancementioning

confidence: 99%

Analysis and Application of Transmission Line Conductors

Laney¹

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Skin effect is usually a concern reserved for radio frequency design and for high current conductors used in utility power distribution. Proximity effect between adjacent conductors has traditionally been a concern for the design of magnetic windings and other applications involving wire bundles. The rise in the ubiquity of high speed bit streams and other signals of very wide bandwidth has broadened the range of applicable contexts and increased the need to account for such effects. This is especially true for transmission lines used to interconnect critical signal paths in applications ranging from microelectronic devices to the signal integrity of printed circuit traces and implementation of system cabling. Optimal conductor design is obviously fundamental to transmission line performance. Researchers have paid considerable attention to the topic but the results are scattered throughout the literature. This thesis collected information on extant conductor designs, and the theoretical considerations behind each solution. A detailed analysis of current flow in a conducting half-space was included as a foundation. The conductor types discussed were solid cylindrical, rectangular, ribbonoid, bimetallic, tubular, laminated, litz, and stranded constructions. Discussions of the performance of stranded shields and conductor roughness effects were included for completeness of understanding.

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Distortion of Fast Pulses by Non-Tem Effects in Coaxial Cables

Cited by 6 publications

References 2 publications

Evidence and effects of higher order modes on the response of guided wave radar-based level sensors

Evidence and effects of higher order modes on the response of guided wave radar-based level sensors

An ultrawideband signal design with power spectral density constraints

Analysis and Application of Transmission Line Conductors

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