Ultra-wideband Synthetic Aperture Radar Imaging: Theory and Applications by Daniel Oloumi A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electromagnetics and Microwaves Department of Electrical and Computer Engineering University of Alberta c Daniel Oloumi, 2016 Abstract 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 UWB- SAR systems with specific range and cross-range resolutions. The effect of the pulse shape, ii 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 mon- itoring 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. iii Preface This thesis is an original work by Daniel Oloumi. Chapter 2 is published as: D.Oloumi, Jui-wen Ting, K.Rambabu,“Design of pulse characteristics for near-field UWB- SAR imaging,“ IEEE Trans. on Microwave Theory and Techniques. vol.64, no.8, pp.2684- 2693, Aug. 2016. Chapter 3 is published as: D.Oloumi, K.Rambabu,“Studying the superluminal behavior of UWB antennas and its ef- fect on near-field imaging,“ IEEE Trans. on Antennas and Propagations, (Accepted with minor revision), ID: AP1510-1634.R2. Chapter 4 is published as: D.Oloumi, M.I. Pettersson, P. Mousavi, K.Rambabu,“ Imaging of oil-well perforations using UWB synthetic aperture radar,” IEEE Trans. on Geoscience and Remote Sensing, (TGRS), vol.53, no.8, pp.4510-4520, Aug. 2015. Chapter 5 is published as: D.Oloumi, K.Rambabu,“ Metal-cased oil well perforation detection using UWB radar tech- niques,“ submitted to IEEE Trans. on Geoscience and Remote Sensing, (TGRS), ID:TGRS- 2016-00933,(Suitable for publication, revision submitted). Chapter 6 is published as: D.Oloumi, K-M.Chan, P.Boulanger, K.Rambabu,“SAGD process monitoring of heavy oil reservoir using radar techniques,“IEEE Trans. on Microwave Theory and Techniques, vol. 64, no. 6, pp. 1884-1895, June 2016. iv Chapter 7 is published as: D.Oloumi, A. Kordzadeh, P.Boulanger, K.Rambabu,“ Breast tumor detection using UWB circular-SAR microwave tomographic imaging ,“ submitted to IEEE Trans. on Microwave Theory and Techniques. TMTT-2016-09-1058,(Suitable for publication, revision submit- ted). D.Oloumi , P.Boulanger, A. Kordzadeh, K.Rambabu ,“ Breast tumour detection using UWB circular-SAR tomographic microwave imaging,” 37th Annual International Confer- ence of the IEEE Engineering in Medicine and Biology Society (EMBC), Milan, 2015, pp. 7063-7066. (Selected as finalist paper) D.Oloumi, P.Boulanger, K.Rambabu,“ Tracking a biopsy needle inside a breast using UWB circular-SAR,“ IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting, Vancouver, BC, 2015, pp. 534-535. I rendered help from the co-authors either in theoretical discussions and or for the mea- surements. v Dedicated to My beloved Family Earn as much education as you can: it’s wealth that nobody can steal from you My grandmother, Tahereh, advice to me RIP Acknowledgements First of all, I would like to thank God for the opportunity to achieve one of my most important goals. It was a long journey with many peaks and valleys, however I was very fortunate to have the support and encouragement of those I would like to thank and acknowledge herby. I would like to extend my gratitude to my Ph.D. supervisor, Prof. Rambabu Karumudi. His limitless support, insight, immense knowledge, and mentorship played a significant role in my success. The timely completion of my thesis would not have been possible without his support and inspiration. In addition to academic support, he has always encouraged me through tough moments, for which I am forever grateful. I would like to express my honest thanks to my lovely wife, Atefeh, who stayed beside me throughout this journey in all its ups and downs. Unquestionably, without her love and support, this accomplishment would be very difficult if not impossible. I would like to give my sincere thanks to my parents Maryam and Amir for the continued love and care that they have provided me throughout my life. I also would like to thank my siblings Elahe and Benjamin and along with the rest of my family and friends for their precious support. I would like to thank my Ph.D. committee members and examiners, Prof. Pierre Boulanger, Prof. Robert Fedosejevs, Prof. Vien Van, and Prof. Mahta Moghadam for insightful com- ments and encouragement. I would like to thank my wrestling coach, Owen Dawkins, who inspired me to get on the mat again as well as my teammates for the priceless moments and experiences that we shared over the last few years as varsity athletes representing the University of Alberta. I would like to thanks, Prof. Hojjat Kashani, my undergraduate supervisor, who inspired me in this field of study. Thinking of my grandparents and my mother in law, who could not join me on this day, but would have loved to, you’re in my heart forever. viii Finally, I would like to acknowledge the financial support provided by Killam, Alberta Innovates Technology Future, IEEE Microwave Theory and Techniques, Andrew Stewart Prize as well as Natural Sciences and Engineering Research Council (NSERC) of Canada. ix Contents 1 Introduction to UWB-Synthetic Aperture Radar 2 1.1 Motivation ..................................... 2 1.2 Radar Systems and UWB Definition ...................... 3 1.2.1 Radar ................................... 4 1.2.2 UWB radars ................................ 5 1.3 SAR Processing .................................. 7 1.3.1 Time domain global back projection technique ............. 7 1.3.2 LSAR image reconstruction ....................... 10 1.3.3 CSAR image reconstruction ....................... 12 1.3.4 Post processing of reconstructed images ................. 13 1.3.5 UWB radar configuration ........................ 13 1.4 Pulse Calibration and Conditioning ....................... 15 1.5 The Contributions of this Thesis ......................... 17 2 Design of Pulse Characteristics for Near-field UWB-SAR Imaging 21 2.1 Introduction .................................... 21 2.2