Near-Field Antenna Arrays for Steerable Sub-Wavelength Magnetic-Field Beams

Alon Ludwig

Sarris group, EM

Abstract:

ubwavelength imaging and focusing of electromagnetic waves has received considerable attention over the past several years. In the near field, subwavelength imaging and focusing devices are based on judiciously formed antenna arrays with closely spaced elements bearing subwavelength features, commonly referred to as meta-screens or near-field plates. In this talk, I will show that such a near-field antenna array can be designed to achieve a two-dimensionally steerable magnetic-field subwavelength beam.

The presentation commences with a summary of relevant results from our prior studies of meta-screens, followed by a description of the magnetic-beam focusing array and its performance. It is then demonstrated that the array operation can be understood based on a simplified circuit model that accounts for the mutual coupling between elements and the radiation resistance. Based on this circuit model, some general underlying properties of the array are inferred, including the existence of a strong resonance that is characterized by opposing currents on neighboring loops. It is suggested to use this inherent resonance when initializing an optimization procedure that tunes the array to maximize the focused beam intensity while eliminating the need in multiple excitation sources. The proposed array may prove useful in a variety of applications ranging from electric actuators and wireless power transfer systems to biomedical imaging and therapy devices.

Biography:

Alon Ludwig received his B.Sc. and Ph.D. degrees in electrical engineering from the Technion - Israel Institute of Technology, in 2000 and 2007, respectively. During the years 2008-2010 he was a postdoctoral associate with the School of Electrical and Computer Engineering at Purdue University. Currently, he is a Postdoctoral Fellow at the University of Toronto. His research interests include efficient frequency and time domain numerical techniques for the solution of electromagnetic scattering problems, near-field antenna arrays for imaging and focusing applications, aspects of electromagnetic mixing formulas in metamaterials, and bianisotropicy and chirality in metamaterials.