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In this paper, the synthesis of arrays for long-distance wireless power transmission (WPT) based on unconventional architectures is addressed. A subarraying technique based on an enhanced version of the Contiguous Partition Method suitably customized in order to efficiently deal with a WPT scenario is presented, and a Compressive Sensing-based method developed in a multi-task Bayesian framework is...
An innovative ground penetrating radar (GPR) inverse scattering (IS) methodology for imaging sparse buried objects is proposed. The developed methodology integrates a customized Bayesian compressive sensing (BCS) solver within a frequency hopping (FH) strategy in order to (i) regularize the IS problem by enforcing sparsity priors on the unknown scatterers as well as to (ii) exploit the multi-chromatic...
A new paradigm for the design of reflectarrays is introduced. The proposed methodology allows the designer to specify constraints/simplifications on the antenna surface current distribution thanks to an innovative exploitation the non-radiating (NR) component, which is regarded a powerful additional degree-of-freedom (DoF) in the synthesis process. An illustrative example is presented, aimed at nulling...
The design of multi-band patch antennas is addressed within the System-by-Design (SbD) paradigm. A fast optimization-driven strategy combining customized tools for the effective exploration of the solution space and the efficient evaluation of the antenna radiation performance is proposed. Toward this aim, an Ordinary Kriging (OK) predictor is used as a surrogate model of the cost function while the...
A subarraying technique based on a novel genetic algorithm (GA) whose operators have been suitably customized in order to deal with integer variables is presented in this paper. The method is aimed to prevent the generation of high-level quantization lobes in the scanned radiation pattern by properly combining a given number of clusters selected from an arbitrarily defined alphabet of tiles of various...
In this contribution, we propose the use of metasurfaces not only to cloak an object but also to change its scattering response in view of camouflage and scattering manipulation applications. We present the analytical formulation for the case of a cylindrical object with the goal of deriving the surface impedance of the surrounding metasurface to make the object appearing as it were either larger...
In the last few years, the possibility to engineer the properties of artificial Metamaterials at microwave, THz, and optical frequencies has represented one of the key factors enabling the study, development, and demonstration of effective electromagnetic cloaks [1]. Indeed, several devices have been proposed which are able to manipulate the wave propagation not only to reduce radar cross section,...
The capability to describe, design, and configure complex devices on a multi-scale basis (e.g., combining their descriptors on a macro-scale, such as the device geometry, and on a micro/nano-scale, such as on the constituting material features) is a very important task in those applicative scenarios where the features of the overall systems can be obtained only as combination of information obtained...
There is nowadays an increasing attention and request towards the study and development of systems and techniques for increasing the human safety and security in all aspects of the everyday life. In this framework, the possibility to perform a non-invasive inspection of structures or objects by means of non-destructive testing and evaluation (NDT-NDE) technologies is of particular interests in several...
Imaging techniques exploiting sparseness-regularized formulations emerged in the last few years as powerful and effective retrieval methods in several heterogeneous scenarios [1] including structural monitoring, non-destructive testing and evaluation, ground penetrating radar imaging, and biomedical diagnosis [2–8]. The success of the this class of algorithms, which are often collectively indicated...
In this work, the problem of efficiently and accurately predicting the scattering coefficient matrices of complex reflectarrays elements is addressed. The solution proposed does not resort to numerically expensive full-wave simulators. On the contrary, it exploits an advanced Learning-by-Example technique which predicts the matrix which describes the behaviour of the wave reflected by the unit cell...
The instantiation/customization of the recently introduced System-by-Design (SbD) paradigm to the solution of multiscale and multiphysics synthesis problems is discussed in this work. Towards this end, the SbD fundamental concepts are illustrated (starting from the composition of elementary functional blocks up to the derivation of an integrated SbD design loop) together with the basic structure and...
The paradigm of Compressive Sensing (CS) has emerged in the last few years as a flexible and powerful methodological strategy to address synthesis and analysis problems arising in wave scattering and propagation engineering. The success of CS techniques is motivated by several factors, including (i) their capability to address sampling/recovery problems overcoming the classical Nyquist/Shannon limits,...
The design of task-oriented metamaterial coatings able to improve the radiation characteristics of reference linear arrays is demonstrated in this paper. Towards this end, the synthesis problem is formulated within the Material-by-Design (MbD) framework and it is solved by means of an advanced Quasi-Conformal Transformation Optics (QCTO) approach. A preliminary numerical example is presented to demonstrate...
A review of the features, potentialities, and applications of Compressive Sensing (CS) methodologies in the solution of computational imaging problems is presented in this work. Towards this end, the most popular formulations for the solution of CS imaging problems at microwave frequencies are illustrated, and the advantages/limitations of current techniques developed in this framework are discussed,...
The design of conformai arrays radiating the same field of reference linear arrangements is addressed within the Material-by-Design (MbD) framework by exploiting a two-step Quasi-Conformal Transformation Optics (QCTO) procedure. Unlike state-of-the-art design methods, the proposed approach allows to enforce that both the array and the coating are conformal to an arbitrary profile. Preliminary numerical...
The System-by-Design procedure is here adopted in order to design in an efficient way a multi-layer mantle cloak which has the aim of reducing the observability of large dielectric cylinders. Indeed, in order to minimize the Scattering Cross Section (SCS) of non-electrically small objects it is necessary to cancel not only the fundamental scattering mode, but also higher modes. The arising design...
The synthesis of compact metamaterial-loaded sectoral or conical horn antennas matching the radiation properties of larger layouts is addressed. Unlike state-of-the-art strategies, the metamaterial lens that fills the miniaturized horn is designed so that the radiated field coincides with that of the reference arrangement both in amplitude and phase. To this end, the synthesis is first recast as a...
Inspection of penetrable objects by using differential evolution together with a recently proposed iterative multiscaling approach is discussed in this Chapter. Several new results are included concerning the reconstruction of inhomogeneous targets under various imaging conditions.
This contribution presents an overview of some innovative methodologies developed at ELEDIA Research Center of the University of Trento in the context of microwave imaging, inverse scattering, and synthesis problems. The focus of this work is on the use of different methodologies and tools for the reconstruction of unknown objects embedded in an inaccessible region when illuminated by a set of electromagnetic...
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