A Novel Tecknioue for Vector Network Measurement

Brunfeldt, David R.; Mukherjee, Somnath

doi:10.1109/arftg.1991.324018

Cited by 8 publications

(8 citation statements)

References 9 publications

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“…These systems offer a high measurement precision and dynamic range, but the system error reduction of multiport MWT systems is complicated and the achievable measurement rate low in the case of a high number of required frequency samples. To overcome these drawbacks, we examined the applicability of the frequency-modulated continuous waves (FMCW) network analysis technique [30] for multiport MWT systems [31], which offers robust and computationally inexpensive system error reduction, resulting in an improved imaging accuracy and reconstruction stability.…”

Section: Data Acquisition and Signal Processingmentioning

confidence: 99%

Fast and Precise Soft-Field Electromagnetic Tomography Systems for Multiphase Flow Imaging

et al. 2018

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In the process industry, measurement systems are required for process development and optimization, as well as for monitoring and control. The processes often involve multiphase mixtures or flows that can be analyzed using tomography systems, which visualize the spatial material distribution within a certain measurement domain, e.g., a process pipe. In recent years, we studied the applicability of soft-field electromagnetic tomography methods for multiphase flow imaging, focusing on concepts for high-speed data acquisition and image reconstruction. Different non-intrusive electrical impedance and microwave tomography systems were developed at our institute, which are sensitive to the local contrasts of the electrical properties of the materials. These systems offer a very high measurement and image reconstruction rate of up to 1000 frames per second in conjunction with a dynamic range of up to 120 dB. This paper provides an overview of the underlying concepts and recent improvements in terms of sensor design, data acquisition and signal processing. We introduce a generalized description for modeling the electromagnetic behavior of the different sensors based on the finite element method (FEM) and for the reconstruction of the electrical property distribution using the Gauss-Newton method and Newton's one-step error reconstructor (NOSER) algorithm. Finally, we exemplify the applicability of the systems for different measurement scenarios. They are suitable for the analysis of rapidly-changing inhomogeneous scenarios, where a relatively low spatial resolution is sufficient.

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Section: Data Acquisition and Signal Processingmentioning

confidence: 99%

Fast and Precise Soft-Field Electromagnetic Tomography Systems for Multiphase Flow Imaging

et al. 2018

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“…For a linear sweep characteristic the LO-Signal can be written as ULO(t) = a(t) * cos{2r-(fo t + 2.T_ tI)} (2) where a(t) denotes the generator amplitude. The generator signal in the test branch is affected by the DUT and the time delay t. B urQ () = a(t -1) --2T)1 cos 2;r ( ( ) + 2 * -I ) +cosH(tr)- (3) For convenience the mixing process of (2) and (3) is modelled by a simple multiplication. After low-pass filtering the IF-signal can be expressed as u.,(Q)h a2Q() lH(Q).cos{2wr{fo+ jt + ) 9H('A for 0 < I s T and r <c T. (4) For determination of (4) the approximation Tr << T is used, which is always valid in practical systems.…”

Section: Principle Of Rf-partmentioning

confidence: 99%

“…For good results even in the micro-or millimetre-wave range complex homodyne receivers are used, as shown by Schneider et al [1] or Geck and Marquardt [2]. As first described by Mukherjee [3] the use of the FMCW-method leads to a significant simplified RF-part of such measuring system. Therefore this principle is very attractive for low cost applications.…”

Section: Introductionmentioning

confidence: 97%

A low cost homodyne reflectometer based on the FMCW method and digital signal processing

Geck¹,

Marquardt²,

Sagebiel

1996

26th European Microwave Conference, 1996

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The application of the well known FMCW-method for homodyne network analysis is presented. A network analyzer based on this principle needs only a simple RFpart and therefore a more complex IF-part which makes extensive use of modern digital signal processing. The system theory is presented and explained with the help of measurements. A measuring system of such kind facilitates low cost, high speed measurements with a certain reduction in measuring precision. The validity of theory is proved by reflectometer measurements in X-and Ka-band.

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“…In this paper, we propose a data acquisition unit for fast, precise and accurate network analysis based on the wellknown technique of frequency modulated continuous waves (FMCW) [27][28][29]. In contrast to conventional CW VNAs, which use the stepped frequency procedure for a broadband sweep, FMCW systems utilize a signal, whose frequency is linearly modulated (frequency ramp), and thus avoid the settling time at each frequency point.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to conventional CW VNAs, which use the stepped frequency procedure for a broadband sweep, FMCW systems utilize a signal, whose frequency is linearly modulated (frequency ramp), and thus avoid the settling time at each frequency point. The method offers very fast measurements without compromising the SNR and DR [27], and is particularly advantegeous for MWI system requiring a large number frequency samples. Furthermore, the hardware complexity of a (metadyne [27]) FMCW VNA is significantly lower than that of a commercial (heterodyne) VNA, and systematic measurement errors can be reduced by digital filtering of the measured signals.…”

Section: Introductionmentioning

confidence: 99%

Fast and precise data acquisition for broadband microwave tomography systems

Mallach

Musch

2017

Meas. Sci. Technol.

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Microwave imaging (MWI) is a noninvasive diagnosis method, which has been investigated for a wide range of applications. MWI techniques include radar-based approaches as well as microwave tomography (MWT). One major challenge designing broadband MWI systems is the development of a data acquisition unit that allows for fast broadband scattering parameter measurements with a high measurement precision and a high dynamic range (DR), at reasonable cost. The cost-performance criteria cannot readily be achieved using commercial, continuous wave (CW) vector network analyzers (VNA) or pulse-based systems. Therefore, in this paper we propose a data acquisition unit, based on the well-known method of frequency modulated continuous wave (FMCW) network analysis. It offers fast scattering parameter measurements without compromising the measurement precision and the DR, and is particularly advantageous for MWI systems requiring a high number of frequency samples. A 2-port metadyne prototype electronics with low hardware complexity was developed, which allows very fast, precise, and accurate reflection and transmission measurements in the frequency range from 0.5 GHz to 5.5 GHz. To the best of the authors’ knowledge, a system with combined performance in terms of bandwidth, sweep time (1 ms), DR (80 dB) and maximum signal-to-noise-and-spurious ratio (65 dB) has not previously been reported. The design, the calibration, and the characterization of the prototype electronics are described in detail, and the measurement results are compared to those obtained with commercial high-end CW VNA. The advantages and limitations of the metadyne FMCW technique compared to the heterodyne CW technique are discussed. The applicability of the prototype electronics and the described calibration technique for microwave imaging has been demonstrated based on measurements using an 8-port MWT sensor and a switching matrix.

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A Novel Tecknioue for Vector Network Measurement

Cited by 8 publications

References 9 publications

Fast and Precise Soft-Field Electromagnetic Tomography Systems for Multiphase Flow Imaging

Fast and Precise Soft-Field Electromagnetic Tomography Systems for Multiphase Flow Imaging

A low cost homodyne reflectometer based on the FMCW method and digital signal processing

Fast and precise data acquisition for broadband microwave tomography systems

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