Upcoming Events


Smart Beaming Of RFID Reader For Data And Power Transfer


Abstract: Nowadays there is an almost unlimited number of monitoring applications in structural health, logistic, security, healthcare and agriculture that are deploying a large number of co-operative wireless microsystems, with sensing capabilities, moving closer to the effective realization of the paradigm of the Internet of Things.

I will discuss one of the main open challenges of these scenarios which is the reliability of maintenance-free devices, with life-time duration, especially from the energy sustainability point of view. Such systems are required to power themselves, by harvesting energy from the ambient, thus eliminating battery needs. RF/microwave energy sources are foreseen as one of the best candidates to comply with energy autonomy, either because they are widely distributed in humanized environments or because they can be efficiently provided on demand. These two different ways of providing RF energy can be referred to as RF energy harvesting (EH) and wireless power transmission (WPT), respectively.

I propose a solution to optimize (minimize) intentional WPT at UHF, by adopting smart beaming techniques at the RFID reader side, with the twofold goal of locating the tag and then of providing on demand the needed RF energy in that precise direction. A dynamic radiating system based on the implementation of Time Modulated Array (TMA) is foreseen to be a very promising solution for the above-mentioned operation, having a much simpler architecture compared to other beam-forming solutions, such as phased arrays or retro-directive arrays. By a two-step real-time beaming implementation of linear TMAs, a smart WPT system is demonstrated: In the first step, the TMA is configured in such a way that the control sequences are designed to allow to get the position of the devices to be energized; such positions are used in the second operative step of the system, to set the time control modulating signals of the entire array for real-time beaming the RF power to the wanted directions. The dynamic nature of TMAs thus allows creating an agile energy-aware reader/transmitter to be adopted in different scenarios, pervasively occupied by battery-less devices.

The procedure allows a flexible design of the TMA-based WPT system, taking into account the impact of different array elements layout and spacing on localization and power transmission performance. Theoretical justification and experimental verification are presented and discussed.

Speaker: Prof. Alessandra Costanzo, University of Bologna, Italy.
Date: 6 June 2018
Time: 10:30 AM to 11:45 AM
Venue: McGill University
Dept of Electrical and Computer Engineering
McConnell Engineering Building
Room ENGMC 603
3480 University
Montreal QC H3A 0E9
Links: Registration


Microwave radar reconstruction algorithm for breast cancer detection


Abstract: Breast cancer is responsible for 25% of all new cancers in Canadian women and is a growing global health concern. While x-ray mammography is the current standard for breast imaging and has benefits for managing local control in women over the age of 50, its false positive rate of up to 20%, inability to reduce mortality, particularly in younger women and its tendency for overdiagnosis, provides opportunities for complementary techniques. Breast microwave imaging is an emerging imaging modality that uses non-ionizing microwave signals to image the breast. Radar-based systems are popular because of their simplicity, but the quality of the images reconstructed from these systems is often low.

This talk will present an iterative microwave radar reconstruction algorithm for breast cancer detection based on the maximum-likelihood expectation-maximization (MLEM) algorithm used in positron emission tomography. The iterative nature of this algorithm allows for the implementation of various correction factors into the signal model. Corrections for the antennas beam pattern and frequency-dependent gain, and for the inhomogeneous propagation speed of the signal in the scan region were implemented. Experimental scans of an array of 3D-printed MRI-based anthropomorphic breast phantoms were used to test and validate the reconstruction algorithm, and the reconstructed images were compared to those produced by a published holographic reconstruction algorithm.

The monostatic MLEM-based radar algorithm produced images with greater signal-to-clutter ratios than those of the holographic algorithm, particularly in the reconstruction of dense breast phantoms, as large as 16 dB in reconstructions of a 3 cm lesion. A multistatic version of the MLEM-based algorithm will also be described, and the images and quality metrics of these reconstructions will be compared with those of experimental monostatic and bistatic scans. The impact of breast density on the visibility of the tumor response in reconstructed images produced by the MLEM-based algorithms and the holographic method will be explored.

The MLEM-based algorithm has demonstrated improvements in both image quality and the identification of the tumor response compared to holographic reconstruction. This talk will demonstrate the advantages of the MLEM-based algorithm, particularly in the reconstructions of dense breasts.

Speaker: Mr. Tyson Reimer, University of Manitoba, Canada.
Date: 11 June 2018
Time: 10:30 AM to 11:30 PM
Venue: McGill University
Dept of Electrical and Computer Engineering
McConnell Engineering Building
Room ENGMC 603
3480 University
Montreal QC H3A 0E9
Links: Flyer, Registration