Precursor field in dispersive medium and its optimality

Dr. Guangran Kevin Zhu

The Edward S. Rogers Sr. Department of Electrical and Computer Engineering (Electromagnetics)

Abstract:

The precursor field refers to the wave energy that is dispersed by the medium/waveguide and proceeds the main signal (although in certain situation it may also follow the main signal.). The field intensity of the precursor field attenuates as a monomial function of distance, which is in contrast to the exponential attenuation experienced by narrow-band signals. This motivates the study of the precursor field in comparison with other waveforms, and the pulse design based on the precursor field for applications in imaging, remote sensing, and communications. We show that the precursor field undergoes less attenuation because the energy of the pulse is reshaped by the medium to a lower frequency range. As the distance gets large, the precursor field coincides with the impulse response of a channel; thus, its optimality is in analogy to the matched filter in digital communication theory. Microwave experiments of the propagation of the channel impulse response demonstrate the sub-exponential attenuation due to the capitalization on the low attenuation rate of low-frequency signals.

Biography:

Guangran Kevin Zhu received the B.Sc. degree and M.Sc. degree from University of New Brunswick, Fredericton, NB, Canada, in 2003 and 2005, in Computer Engineering and Electrical Engineering. He received the Ph.D. degree from McGill University, Montreal, QC, Canada in 2011. From 2001 to 2003, he was an intern with IBM Toronto Software Lab, where he was engaged in the development of the WebSphere E-Commerce software. In Summer 2011, he was a research associate in the Physics department at McGill, working on the parallel Poisson solver in the modelling of the quantum transport properties of atomic and molecular scale nanoelectronic devices. His current research is on modelling wave propagation and scattering in dispersive media and its application in communications and medical imaging.  Dr. Zhu received the McGill Graduate Studies Fellowship in 2005 and the IEEE Antennas and Propagation Society Graduate Fellowship in 2008. He is an avid user of GNU/Linux and Emacs, and enjoy programming in C++ with Boost, Matlab, Linux shell scripts, and Python. More details can be found at http://www.waves.utoronto.ca/~kzhu