BEGIN:VCALENDAR VERSION:2.0 PRODID:-//132.216.98.100//NONSGML kigkonsult.se iCalcreator 2.20.4// BEGIN:VEVENT UID:20260524T093203EDT-8123TM1FfR@132.216.98.100 DTSTAMP:20260524T133203Z DESCRIPTION:Abstract\n\nBreast cancer remains one of the leading causes of mortality among women\, and early detection is essential for improving sur vival rates. X-ray mammography\, the current gold standard\, exposes patie nts to ionizing radiation that limits exam frequency\, while magnetic reso nance imaging is costly and reserved for high-risk cases. Microwave imagin g uses non-ionizing radiation and exploits dielectric contrast between hea lthy and malignant tissues\, making it an attractive low-cost complement t o established diagnostics. Over the last decade\, the RF Breast Cancer Det ection Group at 91ɬÂþ has been developing flexible near-field biosensor arrays mounted on bra-like supports with the long-term vision of a comfortable device suitable for frequent screening.\n\nBuilding on this platform\, my work first redesigned the sensing array to improve near-fie ld performance. I developed several generations of 3–5 GHz PDMS-based near -field antennas\, assembled into arrays of up to 16 elements with hexagona l enclosures to concentrate the electromagnetic fields inside the tissue. Full-wave simulations and measurements showed that the new array suppresse d surface-wave crosstalk between elements and reduced back radiation compa red ith the legacy polyimide stepped-monopole sensor. Integrated into a he mispherical structure\, the antennas were validated over carbon-based brea st phantoms replicating the dielectric properties of fat\, glandular tissu e\, skin\, and tumour inclusions.\n\nTo eliminate reliance on expensive an d bulky laboratory setups\, such as a vector network analyzer (VNA) or cus tom ultrawideband (UWB) electronics normally used with these arrays\, I de veloped a low-cost software-defined radio (SDR) RF transceiver system base d on the open-source USRP platform. The complete system was characterized in terms of RF performance and showed results comparable to the VNA in the frequency range and power levels of interest. A denoising autoencoder neu ral network was then trained using VNA data as a reference to reduce the r emaining performance and stability gap by suppressing unwanted spectral ar tefacts and trends in the SDR signals.\n\nOn the image reconstruction side \, after revisiting conventional time-domain and frequency-domain beamform ers facilitated by the Chirp-Z transform (CZT)\, I introduced a new full-w ave confocal beamformer that embeds simulated near-field Green’s functions of the PDMS sensor array. Using full-wave HFSS models and measured data\, I benchmarked these beamformers with standard image quality metrics. This framework allowed me to assess the performance of the newly designed syst em against the established 91ɬÂþ UWB prototype\, showing that it preserve d imaging performance at a fraction of the hardware cost and size.\n\nLast ly\, this thesis extends the microwave scattering principles used for brea st screening to the problem of skin cancer screening\, with the goal of es tablishing a numerical method for skin lesion characterization. The propos ed approach uses a pair of Vivaldi antennas specifically designed to propa gate surface waves along the tissue–air boundary\, from which the effectiv e permittivity of skin lesions is estimated. The underlying theory was val idated through full-wave simulations\, and three different Vivaldi prototy pes were designed and fabricated to explore practical realizations.\n DTSTART:20260313T140000Z DTEND:20260313T160000Z LOCATION:Room 603\, McConnell Engineering Building\, CA\, QC\, Montreal\, H 3A 0E9\, 3480 rue University SUMMARY:PhD defence of Milad MokhtariSangdehi – Low-power Microwave Applica tions in Healthcare: Breast Cancer Detection and Skin Lesion Diagnosis URL:/ece/channels/event/phd-defence-milad-mokhtarisang dehi-low-power-microwave-applications-healthcare-breast-cancer-371807 END:VEVENT END:VCALENDAR