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| 2. |
- Ferndahl, Mattias, 1973, et al.
(författare)
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A General Statistical Equivalent-Circuit-Based De-Embedding Procedure for High-Frequency Measurements
- 2008
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 56:12, s. 2692-2700
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Tidskriftsartikel (refereegranskat)abstract
- A general equivalent-circuit-based method for the de-embedding of scattering parameters is presented. An equivalent circuit representation is used to model the embedding package. The parameters in the models are estimated with a statistical method using measured data from all de-embedding standards jointly together. Hence, it is possible to assess parameter estimates and their variance and covariance due to measurement uncertainties. A general de-embedding equation, which is valid for any five-port with a defined nodal admittance matrix, is derived and used in the subsequent de-embedding of measured device data. Different equivalent circuit models for the embedding network are then studied, and tradeoffs between model complexity and uncertainty are evaluated. Furthermore, the influence of varying number and combinations of de-embedding standards on the parameter estimates is investigated. The method is verified, using both measured and synthetic data, and compared against previously published work. It is found to be more general while keeping or improving accuracy.
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| 3. |
- Fhager, Andreas, 1976, et al.
(författare)
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Clinical Diagnostics and Treatment with Electromagnetic Fields
- 2010
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Ingår i: 4th European Conference on Antennas and Propagation, EuCAP 2010; Barcelona; Spain; 12 April 2010 through 16 April 2010. - 9788476534724 ; , s. C15P2-1
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Konferensbidrag (refereegranskat)abstract
- There is a need for novel diagnostic and treatment systems to overcome the limitations with todays modalities. Microwave and THz based system has the potential to become both sensitive and specific in several applications. In this paper we discuss several applications that are currently being developed at the Chalmers University of Technology.
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| 4. |
- Fhager, Andreas, 1976, et al.
(författare)
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Progress in clinical diagnostics and treatment with electromagnetic fields
- 2011
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Ingår i: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9788882020743 ; , s. 1936-1937
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Konferensbidrag (refereegranskat)abstract
- There is a need for novel diagnostic and treatment systems to overcome the limitations with todays modalities. Microwave and THz based system has the potential to become both sensitive and specific in several applications. In this paper we discuss several applications that are currently being developed at the Chalmers University of Technology.
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| 5. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Accuracy evaluation of time domain measurement systems for microwave tomography
- 2009
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Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781424428045 ; , s. 1441-1444
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Konferensbidrag (refereegranskat)abstract
- The measurement accuracy of time domain systemsfor microwave tomography are evaluated through system levelsimulations and compared with that of a network analyzerbased frequency domain system. In the analysis, both a timedomain ultra-wideband (UWB) impulse and multiband systemarchitectures are considered. It is shown that the measurementerror of the time domain systems mainly comes from analogto digital (A/D) conversion. For a simple comparison case, therelative measurement error involved in an estimated objectresponse signal from the time domain UWB impulse system andUWB multiband system measurements are around three timesand ten times higher than that from frequency domain system.
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| 6. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Accuracy Evaluation of Ultrawideband Time Domain Systems for Microwave Imaging
- 2011
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 59:11, s. 4279-4285
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Tidskriftsartikel (refereegranskat)abstract
- We perform a theoretical analysis of the measurement accuracy of ultrawideband time domain systems. The theory is tested on a specific ultrawideband system and the analytical estimates of measurement uncertainty are in good agreements with those obtained by means of simulations. The influence of the antennas and propagation effects on the measurement accuracy of time domain near field microwave imaging systems is discussed. As an interesting application, the required measurement accuracy for a breast cancer detection system is estimated by studying the effect of noise on the image reconstructions. The results suggest that the effects of measurement errors on the reconstructed images are small when the amplitude uncertainty and phase uncertainty of measured data are less than 1.5 dB and 15 degrees, respectively.
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| 7. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Accuracy investigation of an ultra-wideband time domain microwave imaging system
- 2011
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Ingår i: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9788882020743 ; , s. 1928-1932
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Konferensbidrag (refereegranskat)abstract
- We investigate the measurement accuracy of an ultra-wideband time domain microwave tomography system. A phantom is imaged by means of the system and the reconstructed images are compared to those obtained with an ultra-wideband frequency domain system. The results suggest that the permittivity reconstructions obtained by means of the time domain and the frequency domain systems are very similar to each other, but the conductivity profile reconstructed from time domain measurements presents worse quality than that obtained from frequency domain measurements.
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| 8. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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An ultrawideband microwave medical diagnostic system: Design considerations and system performance
- 2012
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Ingår i: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012. Prague, 26-30 March 2012. - 9781457709180 ; , s. 3664-3668
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Konferensbidrag (refereegranskat)abstract
- We discuss several issues in the design of an ultra-wideband microwave system dedicated to medical diagnostics. Based on the discussion, a FPGA-based time domain microwave diagnostic system is proposed. The noise sources of the system are identified and the system noise performance is analyzed. As an example, a 2-D antenna system is considered and the measurement signal to noise ratios are evaluated.
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| 9. |
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| 10. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Design and Performance Evaluation of a Time Domain Microwave Imaging System
- 2013
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Ingår i: International Journal of Microwave Science and Technology. - : Hindawi Limited. - 1687-5826 .- 1687-5834. ; 2013, s. Art. no. 735692-
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Tidskriftsartikel (refereegranskat)abstract
- We design a time domain microwave system dedicated to medical imaging. The measurement accuracy of the system, that is, signal-to-noise ratio, due to voltage noise and timing noise, is evaluated. Particularly, the effect of coupling media on the measurement accuracy is investigated both numerically and experimentally. The results suggest that the use of suitable coupling media betters the measurement accuracy in the frequency range of interest. A signal-to-noise ratio higher than 30 dB is achievable in the range of 500 MHz to 3 GHz when the effective sampling rate is 50 Gsa/s. It is also indicated that the effect of the timing jitter on the strongest received signal is comparable to that of the voltage noise.
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