Multi-Plane Magnetic Near-Field Data Inversion Using the Source Reconstruction Method

Abstract

In this work, we use the electromagnetic inversion (EI) framework to develop/improve algorithms for the purpose of antenna design and characterization. Broadly speaking, antennas are any device, object, or system that can transform energy in the form of guided waves to energy in the form of radiated waves in space. In our increasingly wireless technology landscape, many different types of antennas are being analyzed and developed for a variety of applications. Therefore a flexible design/characterization methodology is required to support our future wireless engineering needs.To this end, we employ an EI methodology that allows the flexibility to develop novel antenna characterization and design algorithms in a variety of applications. In general, electromagnetic inversion enables the determination of an electromagnetic property of interest (e.g., relative permittivity or equivalent current distribution) in an investigation domain by processing some type of electromagnetic data (e.g., complex electric field, phaseless data, or far-field performance criteria) on a separate measurement/desired data domain wherein the investigation and data domains can be arbitrarily shaped; our methodology allows for this flexibility to be utilized. Through the use of this methodology and the electromagnetic surface and volume equivalence principles we develop EI algorithms to contribute to the areas of metasurface design, microwave imaging, and dielectric lens/antenna design. Specifically, (i) we develop and demonstrate a gradient-based EI algorithm that can directly design the circuit admittance profiles of metasurfaces from desired complex or phaseless (magnitude-only) magnetic field data on an external data domain, (ii) we develop and verify inverse scattering algorithms to reconstruct dielectric profiles from phaseless synthetic and experimentally measured data, and finally (iii) we introduce a combined inverse source and scattering technique to tailor electromagnetic fields by designing passive, lossless, and reflectionless dielectric profiles to transform an existing electromagnetic field distribution from a known feed to one that satisfies desired far-field performance criteria such as main beam directions, null locations, and half-power beamwidth. First, I would like thank my advisor and friend Dr. Puyan Mojabi for his guidance throughout my academic journey and for inspiring me to begin the journey in the first place all those years ago in his antennas course at the end of my B.Sc. Thanks also to my friends and colleagues Dr. Trevor Brown, Chen Niu, and Dr. Nozhan Bayat for making my time at the University of Manitoba an absolute joy. I would like to express my gratitude to my Ph.D. internal committee members Dr. Ian Jeffrey, Dr. Jason Fiege, and my external committee member Dr. Andrea Massa for taking the time to help me improve my thesis. Lastly, I'd like to thank the

On the Use of Electromagnetic Inversion for Metasurface Design

“…For example, electromagnetic inversion algorithms can invert phaseless (amplitude-only) near-field measurements [18]. In addition, they are not merely limited to canonical measurement surfaces (e.g., planar, cylindrical, spherical), and work with arbitrarily shaped measurement domains [19]. Moreover, electromagnetic inversion algorithms can systematically incorporate prior information into their formulation to enhance the resulting reconstruction accuracy [20].…”

“…In this case, the use of electromagnetic inverse source algorithms is advantageous. (This advantage of the electromagnetic inverse source algorithms has been utilized in near-field antenna measurements, e.g., see [19]. )…”

“…We have found this two step procedure to greatly improve the convergence and stability of the solution. Lastly, it should be noted that the functionals in (18) and (19) are for the general case with fields radiating in 3D. For 2D problems, A ξ2 is simply set to zero and the same formulation can be used as written.…”

Metasurface Design Using Electromagnetic Inversion

“…For example, electromagnetic inversion algorithms can invert phaseless (amplitude-only) near-field measurements [55]. In addition, they are not merely limited to canonical measurement surfaces (e.g., planar, cylindrical, spherical), and work with arbitrarily shaped measurement domains [68]. Moreover, electromagnetic inversion algorithms can systematically incorporate prior information into their formulation to enhance the resulting reconstruction accuracy [69].…”

“…In this case, the use of electromagnetic inverse source algorithms is advantageous. (This advantage of the electromagnetic inverse source algorithms has been utilized in near-field antenna measurements, e.g., see [68]. )…”