| 31. |
- 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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| 32. |
- Zeng, Xuezhi, 1980, et al.
(författare)
-
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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| 33. |
- Zeng, Xuezhi, 1980, et al.
(författare)
-
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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| 34. |
- 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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| 35. |
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| 36. |
- 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-
-
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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| 37. |
- Zeng, Xuezhi, 1980, et al.
(författare)
-
Development of a Time Domain Microwave System for Medical Diagnostics
- 2014
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 1557-9662 .- 0018-9456. ; 63:12, s. 2931-2939
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a time-domain system dedicated to medical diagnostics has been designed, a prototype has been built and its performance has been evaluated. Measurements show that the system has a 3-dB bandwith of about 3.5 GHz and a signal to noise ratio over 40 dB in the frequency range about 800 MHz to 3.8 GHz. The system has been used to perform a microwave tomographic image reconstruction test. The same target was reconstructed based on data measured with a network analyzer. A comparison between the images shows very small differences, and proves the functionality of the time domain system.
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| 38. |
- Zeng, Xuezhi, 1980, et al.
(författare)
-
Experimental Investigation of the Accuracy of an Ultrawideband Time-Domain Microwave-Tomographic System
- 2011
-
Ingår i: IEEE Transactions on Instrumentation and Measurement. - 1557-9662 .- 0018-9456. ; 60:12, s. 3939-3949
-
Tidskriftsartikel (refereegranskat)abstract
- The measurement accuracy of an ultrawideband (UWB) time-domain microwave-tomographic system is investigated. In order to make an assessment of the random variation of the measurements, the measurement repeatability of the system is evaluated by comparison with an UWB frequency-domain system. A phantom is imaged with the time-domain microwave-tomographic system, and the reconstructed images are compared with those obtained by using the frequency-domain system. The results suggest that with the averaging tens of measurements, the time-domain system can achieve the same level of measurement repeatability as that of the frequency-domain system in the interesting frequency range of microwave tomography. The imaging results, however, indicate that the phantom reconstruction does not require such high measurement accuracy. The permittivity profile of the phantom reconstructed from the nonaveraging time-domain measurements is very similar with that obtained by means of the frequency-domain system.
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| 39. |
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| 40. |
- Zhang, Bing, 1982, et al.
(författare)
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Attempt of the Metallic 3D Printing Technology for Millimeter-Wave Antenna Implementations
- 2016
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Ingår i: Asia-Pacific Microwave Conference, APMC 2015. ; 2
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Konferensbidrag (refereegranskat)abstract
- 3D metallic printing technology is attempted to implement millimeter-wave (mmWave) antennas. Based on laser beam melting (LBM) technology, the cost and turnaround time of metallic horn antenna fabrication is effectively reduced compared with traditional milling and injection moulding. A conical and a pyramidal horn antenna are printed in 316L stainless steel, both of which demonstrate satisfactory performance compared with simulation, as well as comparable performance with commercial horn antennas. Surface roughness of the printed horn antennas are measured and analyzed, showing improvement upon former designs. The 3D printing technology proves its great potential for further exploration.
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