IEEE NCS AP-S/MTT-S Chapter

Dr. Ahmad Hoorfar: Electrodynamics of Space-Filling Curves and their Antenna and Metamaterial Applications

Time: Friday, October 13, 2023 at 12:00 pm MDT

Location: University of Alberta – DICE 7-395 (Pizza served)

Ahmad Hoorfar is a professor of electrical and computer engineering, the ECE department’s graduate chair, and the founder and director of Antenna Research Laboratory at Villanova University. He received his B.S. in electronics engineering from the University of Tehran and the M.S. and Ph.D. degrees in electrical engineering from the University of Colorado Boulder, His research contributions over the years have covered areas in electromagnetic field theory, numerical modeling and novel designs of multifunction printed and low-profile antennas, metamaterial media and surfaces, inverse scattering, microwave sensing and imaging, and stochastic optimization methods. He has been a pioneer in development and applications of evolutionary and global algorithms in electromagnetics, development of electromagnetic-based techniques for through-the-wall radar imaging (TWRI) and ground penetrating radar (GPR), compressive sensing applied to GPR and TWRI, and the use of the mathematical concept of space-filling curves in design of electrically small antennas, RFID tags, artificial magnetic conductors, and metasurfaces.

Dr. Hoorfar was the recipient of Villanova University’s Outstanding Faculty Research Scholar Award in 2007, and the recipient of Philadelphia section’s ‘IEEE chapter of the year award’ for his leadership in chairing the AP/MTT joint chapter in 1995. His students have won top prizes in student best paper competitions at several IEEE and other international symposia, He was the general chair of the 12th and 13th Benjamin Franklin Symposia in Microwave and Antenna Technology held in 1994 and 1995, and co-organizer of the 22nd Antenna Measurement Technique Association (AMTA) Symposium in 2000, and on the organizing committee of 2003 and 2018 IEEE International Microwave Symposia held in Philadelphia. He has served on the review board of various IEEE and other technical publications on antennas, microwaves, and remote sensing in the last thirty years. He has also been on the technical program committees of numerous international symposia and conferences, including IEEE AP-S, IEEE MTT, IEEE Aerospace, IEEE Radio and Wireless, IEEE Radar Conference, International Union of Radio Science (URSI), and Progress in Electromagnetic Research symposia. He spent his sabbatical leave in 2002 and 2009 at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, where he contributed to the development of a general optimization code for design of feed horns for NASA’s deep space communication network.

Abstract

The concept of space–filling curves has been a subject of study in the mathematics literature since the late part of the 19th century. These curves are, in general, continuous mappings from a normalized one- dimensional interval [0,1] to a normalized two-dimensional region, [0,1]×[0,1] , and for each case the curve passes through every point in the 2-D region in the limit of infinite iteration order. The most widely used of these curves is ones proposed by G. Peano and David Hilbert in 1890 and 1891, respectively. From the electromagnetics, scattering, and antenna viewpoints the space-filling curves are very attractive since they offer a resonant structure that could have a very small footprint as one increases the step-order in iterative filling of a 2-D region. Space-filling curves, however, are a subset of much larger class of curves in Graph theory, called Grid-Graph Hamiltonian Paths (GG-HP) and Cycles (GG-HC).

In this lecture, the fundamental electrodynamics of Space-filling curves and Grid-Graph Hamiltonian Paths in terms of their scattering properties, polarizability, and multiband/wideband functionality, and their roles in development of low-profile, electrically small and reconfigurable antennas, metamaterials, and metasurfaces for antenna beam-shaping will be given. In particular, we describe use of the space-filling curve and Hamiltonian Path fractal elements in development of wideband but miniaturized top loaded monopoles, ultra-passive RFID tags, polarization insensitive high-impedance surfaces, electrically-thin microwave absorbers, SNG and DNG metamaterials, and metasurfaces with non-uniformly spaced inclusions for beam shaping of printed antennas. We will discuss salient features of these novel structures and will describe physical insights into the theoretical and measured results.

Reminder for all in-person attendees

Please only attend the event if you are feeling well; anyone feeling sick must stay home.