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Ultra-Wideband Time Domain Measurement Systems for Microwave Tomography

Xuezhi Zeng (Institutionen för signaler och system, Biomedicinsk elektromagnetik)
: Chalmers University of Technology, 2010. - 117 s.
[Licentiatavhandling]

As a potential imaging modality for biomedical applications, microwave tomography has attracted a lot of interests in recent years. With microwave tomography, microwave signals are transmitted into the biological tissues and the scattered fields are recorded. By making use of the received information, the dielectric property profiles of the tissues are quantitatively reconstructed. Based on the difference in dielectric properties, tissues are differentiated and consequentially can be imaged. It has been shown that the reconstructions from wideband data present very good quality with high spatial resolution and high accuracy. In our previous work, the wideband data were obtained in frequency domain with a vector network analyzer, which was time consuming and expensive. An ultra-wideband time domain measurement system has the advantage of fast measurement of wideband data, which is preferable for the clinical applications. A time domain measurement system is either based on equivalent time sampling or real time sampling. In this thesis, the system architectures and work principles of ultra-wideband time domain measurement systems based on these two different sampling strategies are described. In comparison with a frequency domain measurement system, a time domain system, especially that with real time sampling, has lower measurement accuracy due to the poor signal to noise ratio. In this thesis, the accuracy analysis of time domain measurement systems are carried out, which includes the identification of the error sources, the modeling of different types of errors and the terminologies of interest for evaluating the measurementaccuracy. The effects of measurement error on the image reconstruction is also investigated by taking a 2-D breast model as an example. Last, an ultra-wideband time domain experimental system for microwave tomography is presented. Its measurement repeatability is evaluated and phantom reconstructions made from the time domain measurements are compared with those obtained by using a wideband frequency domain system

Nyckelord: Microwave Tomography, Ultra-Wideband, Time DomainMeasurement, Frequency Domain Measurement, Measurement Error, EquivalentTime Sampling, Real Time Sampling



Denna post skapades 2010-05-18. Senast ändrad 2010-11-09.
CPL Pubid: 121681

 

Institutioner (Chalmers)

Institutionen för signaler och system, Biomedicinsk elektromagnetik

Ämnesområden

Elektroteknik

Chalmers infrastruktur

Relaterade publikationer

Inkluderade delarbeten:


Accuracy evaluation of time domain measurement systems for microwave tomography


Examination

Datum: 2010-06-09
Tid: 13:15
Lokal: EB room, EDIT building
Opponent: Mikael Karlsson, FOI

Ingår i serie

R - Department of Signals and Systems, Chalmers University of Technology