A new implementation of a multiport automatic network analyzer

Ferrero, A.; Pisani, U.; Kerwin, Kevin

doi:10.1109/22.168766

Cited by 64 publications

(19 citation statements)

References 14 publications

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“…Direct measurements of the S-parameters were performed on a Rohde & Schwarz ZVL3 vector network analyzer (VNA) at 127.8 MHz following a full two-port Short-Open-Load-Thru (SOLT) calibration that accounts for cable losses and phase shifts [40], [41]. The cables are attached to SMA-type RF connectors soldered across the port locations on the coils.…”

Section: Measurementsmentioning

confidence: 99%

Stray Capacitance Between Magnetic Resonance Imaging Coil Elements: Models and Application to Array Decoupling

Maunder

Daneshmand

Mousavi

et al. 2013

IEEE Trans. Microwave Theory Techn.

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The role of capacitive coupling between RF coil elements of MRI arrays is studied extensively in this paper and comprehensive models are obtained. At higher MRI frequencies, capacitive coupling greatly impacts coil coupling and therefore cannot be neglected. We compare lumped and distributed capacitance models and show that they correctly predict impedance variations due to stray and intentional mutual capacitance. The distributed model takes into account the dispersed nature of the mutual impedance, and it is more accurate than the lumped model. The value of stray capacitance obtained by fitting simulated results is shown to depend strongly on substrate and phantom permittivity, while being mostly invariant to changes in frequency. A novel result of this investigation is a method of completely eliminating mutual impedance between adjacent coils, including the mutual resistance. Until recently it was believed that only mutual reactance could be eliminated with lossless passive circuits. The SNR performance of two and four coil arrays with varying degrees of coupling is compared, showing that there is no SNR degradation when the mutual resistance is eliminated in addition to mutual reactance. This result has applications in arrays used in transmission, where mutual resistance leads to losses that degrade transmit efficiency.

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Section: Measurementsmentioning

confidence: 99%

Stray Capacitance Between Magnetic Resonance Imaging Coil Elements: Models and Application to Array Decoupling

Maunder

Daneshmand

Mousavi

et al. 2013

IEEE Trans. Microwave Theory Techn.

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“…In 1995, Bockelman and Einsenstadt [1] introduced so-called mixed-mode -parameters to extend the classical single-ended power wave theory [2] to the differential case. Since then, the characterization through mixed-mode -parameters has become rather common, either using traditional multiport vector network analyzers (VNAs) rather then dedicated mixed-mode ones [3], [4].…”

Section: Introductionmentioning

confidence: 99%

Generalized mixed-mode S-parameters

Ferrero

Pirola

2006

IEEE Trans. Microwave Theory Techn.

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118

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This paper presents an innovative approach to extend the -parameter definition to multiport networks having conventional single-ended and differential ports, as is the case for operational amplifiers, transformers and baluns. To give maximum generality to this technique, for example, allowing for complex -parameter reference impedances, the mathematical derivation will be carried out with the most general definition of the -parameters. The presented approach gives the same results already published for circuits with differential ports only when the required simplifications are applied.

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“…The previously discussed technique of combining two port calibrations with renormalization is not possible due to the limited fabric, but a direct four port calibration is possibIe (due to the test coupler positioning). The fulIy referenced approach of [4] is also no longer possible. When attempting a direct four port calibration in the test set of Fig.…”

Section: Each Gray Box Represents An Spdt Terminating Switchmentioning

confidence: 99%

LRL/LRM modifications for sinlified high frequency multiport/differential measurements

Martens¹,

Judge²,

Bigelow³

64th ARFTG Microwave Measurements Conference, Fall 2004.

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As multiport and differential VNA measurement needs move beyond 50 GHz, switching complications increase. PIN and FET switch insertion losses and costs increase enough that semi-complete test set switching fabrics are not always practical. In addition, system requirements may preclude optimal reference coupler placement. These issues lead to some complications with the traditional switch correction techniques used With the LRLiLRM class of calibrations. An approach based on a two-tier load match correction has been implemented to help handle the pathology of this test set type since some load match correction is considered hportant in many cases. When comparisons to traditional switch-corrected measurements are possible, the results are nearly identical. Single-ended and differential measurements to 65 GHz are presented to illustrate the technique. 141 0-7803-8858-5/05/$20.00~2005 IEEE

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A new implementation of a multiport automatic network analyzer

Cited by 64 publications

References 14 publications

Stray Capacitance Between Magnetic Resonance Imaging Coil Elements: Models and Application to Array Decoupling

Stray Capacitance Between Magnetic Resonance Imaging Coil Elements: Models and Application to Array Decoupling

Generalized mixed-mode S-parameters

LRL/LRM modifications for sinlified high frequency multiport/differential measurements

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