Author: Daniel OloumiPublisher:
ISBN:
Category : Imaging systems
Languages : en
Pages : 179
Book Description
Ultra wideband (UWB)- synthetic aperture radars are emerging devices that are ideal for sensing and imaging applications in many special conditions such as monitoring subsurfaces, through-wall imaging, non-destructive characterization of materials, oil reservoir monitoring, weather forecasting, geo mapping, microwave holography for tissue imaging, and breast tomography to identify tumors. The exceptional characteristics of UWB radars, including high spatial resolution, low probability of interfering with other radio frequency (RF) signals, low power spectral density and compact size make them suitable for numerous applications. Moreover, their low power consumption allows them to operate on batteries, lending them to portable applications. Oil reservoir monitoring using UWB radar is a new trend in the oil and gas industry for reservoir management and improving production. Monitoring perforations'conditions in metal or concrete-cased oil wells can provide valuable information for oil well maintenance and process optimization. Moreover, observing steam chamber growth in a heavy oil reservoir using radar technology will provide feedback to control steam flow to enhance oil extraction in the steam assisted gravity drainage (SAGD) process. Radar imaging is a developing imaging modality for biomedical applications to study functional and pathological conditions of soft tissue. Radar imaging offers a safe, portable, cost-effective and near real-time imaging supplement for the non-invasive assessment of acute and chronic soft tissue conditions. Microwave imaging may turn out to be a simple and efficient method to perform breast imaging capable of providing adequate image resolutions for diagnosis. This thesis focused on the applications of UWB-synthetic aperture radar (SAR) systems for oil reservoir monitoring and breast tumor imaging; both applications share a requirement for high image resolution. The theory part investigates the design procedure for UWBSAR systems with specific range and cross-range resolutions. The effect of the pulse shape, bandwidth, integration angle, and signal-to-noise ratio (SNR) of the received pulse on the image resolution is comprehensively studied. To enhance the image resolution, pre-processing of the received pulses with envelope detection is proposed. Superluminal phenomenon and UWB pulse propagation in the near-field of an antenna is studied. The apparent superluminal pulse velocity is due to the pulse reshaping of the radiated pulse in the near-field of the antenna. The effect of pulse velocity on the quality of reconstructed images is demonstrated. The application part looks at the suitability of UWB-SAR for oil reservoir monitoring, such as perforation imaging in concrete- and metal-cased oil wells and steam chamber monitoring in heavy oil reservoir. High-quality images are reconstructed using a combination of UWB radar and SAR processing along with the proposed algorithms to improve image quality. The investigation includes positive image generation to enhance image sharpness, and near-field imaging procedure. Practical considerations for SAGD process monitoring such as power budget and heterogeneity analysis of a heavy oil reservoir using UWB radar are studied. The application of UWB-circular synthetic aperture radar (CSAR) for breast tumor imaging is also demonstrated. Tomographic image reconstruction was carried out using a time domain global back projection technique adapted to circular trajectory data acquisition. The suitability of this technique for breast tumor detection and imaging is demonstrated through experiments on a 3D printed breast phantom, developed based on a human breast MRI, which emulates the breast in terms of structures and their electrical properties. The measurement results demonstrated the utility of UWB-CSAR for breast tumor imaging.