Development And Implementation Of Ultra-Wideband Sensing System For Microwave Breast Imaging
| dc.contributor.author | Tiang, Sew Sun | |
| dc.date.accessioned | 2016-11-23T02:47:43Z | |
| dc.date.available | 2016-11-23T02:47:43Z | |
| dc.date.issued | 2014-09 | |
| dc.description.abstract | Since the allocation of the frequency band from 3.1 GHz to 10.6 GHz by the U.S. Federal Communications Commission (FCC) for commercial use, ultra-wideband (UWB) systems have become increasingly prevalent in microwave imaging applications. While designing wideband antennas has been extensively research, especially for use in breast imaging, practical implementation of UWB sensing system remains a challenge owing to the bulky configurations of most designs. A preferred design should be small planar type antenna that can be placed directly on the target. In this study, a novel microstrip line fed wide-slot antenna featuring a compact size of 16 mm × 16 mm, P-shaped slot, and a simple tuning stub design has been developed. The antenna was optimized for operation from 4.91 GHz to 11.0 GHz, with a good agreement between the simulation results and experimental data over a very wide impedance bandwidth. The antenna demonstrated an omnidirectional radiation pattern in the xy- and yz-planes at low frequencies. Its directionality was found to increase with increasing frequency due to the presence of higher order harmonics, while its omnidirectional characteristic was maintained. The time-domain analysis showed that the antenna has relatively distortionless characteristics with a pulse width averaging at 0.625 ns. The fidelity factor was within the acceptable limit of more than 0.6, although it decreases slightly with increasing distance between the transmitter and receiver. The standard deviation of group delay in free space is lower than in vegetable oil for both adjacent and opposite geometries. The phase distortion was minimal, as indicated by consistent small variation of less than 0.254 in standard deviation of the group delay in all cases. The antenna was integrated with an improved acquisition system and a refined delay and-sum algorithm for sensing and mapping of cancerous breast tissues. The system was tested using fatty and glandular breast phantoms in free space and vegetable oil. The reconstructed images revealed the difficulty in accurately identifying the tumour position due to power dissipation into the liquid medium. Despite the presence of clutters, it was possible to obtain a fairly accurate reconstruction for both the homogeneous and heterogeneous models with resolution reaching 5 mm in both free space and oil media. This accuracy is sufficiently adequate for detecting cancerous cells at its early stage of development. The reconstruction was found to be more accurate in free space than in oil medium, as the latter would lead to more cluttering and multiple reflections. The system was developed in such way that it can be used directly with real breast cancer patients in future work as it avoids the complexity of operating and maintaining a coupling medium like oil. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/3167 | |
| dc.subject | Ultra-wideband (UWB) systems have become increasingly prevalent | en_US |
| dc.subject | in microwave imaging applications. | en_US |
| dc.title | Development And Implementation Of Ultra-Wideband Sensing System For Microwave Breast Imaging | en_US |
| dc.type | Thesis | en_US |
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