Full-Wave Verification of an Electromagnetic Inversion Metasurface Design Method

Antennas Wirel. Propag. Lett.

Vahabzadeh

Caloz

et al. 2020

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A method based on electromagnetic inversion is extended to facilitate the design of passive, lossless, and reciprocal metasurfaces. More specifically, the inversion step is modified to ensure that the field transformation satisfies local power conservation, using available knowledge of the incident field. This paper formulates a novel cost functional to apply this additional constraint, and describes the optimization procedure used to find a solution that satisfies both the user-defined field specifications and local power conservation. Lastly, the method is demonstrated with a two-dimensional (2D) example.

Section: Resultsmentioning

confidence: 99%

Electromagnetic Inversion With Local Power Conservation for Metasurface Design

Antennas Wirel. Propag. Lett.

Vahabzadeh

Caloz

et al. 2020

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“…In order to simulate the metasurfaces using commercial software, we employ a three-layer admittance sheet topology [23], [35]- [37] for each unit cell as shown in Figure 4. The conversion from the susceptibility profiles to the admittance sheet model is performed using the procedure in [38]. At a given unit cell, we start by rearranging (33) into the ABCD representation of a two-port network as…”

Section: Conversion To the Three-layer Modelmentioning

confidence: 99%

Cascaded Metasurface Design Using Electromagnetic Inversion With Gradient-Based Optimization

IEEE Trans. Antennas Propagat.

Mojabi

2022

This paper presents an electromagnetic inversion algorithm for the design of cascaded metasurfaces that enables the design process to begin from more practical output field specifications such as a desired power pattern or far-field performance criteria. Thus, this method combines the greater field transformation support of multiple metasurfaces with the flexibility of the electromagnetic inverse source framework. To this end, two optimization problems are formed: one associated with the interior space between two metasurfaces, and the other for the exterior space. The cost functionals corresponding to each of these two optimization problems are minimized using the nonlinear conjugate gradient algorithm with analytic expressions for the gradient operators. A total variation regularizer is incorporated into the optimization procedure to favour smooth field variations from one unit cell to the next. The numerical implementation of the developed design procedure is presented in detail along with several two-dimensional (2D) simulated examples to demonstrate the capabilities of the method.

“…However, this is usually not sufficient to complete the metasurface design process. Physically implementing a metasurface directly from its associated GSTC parameter profile is not done in practice, instead, the GSTC parameters are often transformed to microwave circuit parameters such as impedance, admittance, or scattering parameters [7,43,[83][84][85]95] so that the appropriate subwavelength metasurface elements can be designed in a separate step [7,43].…”

Section: Introductionmentioning

confidence: 99%

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

Narendra

2018 18th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM)

Bayat

et al. 2018

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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