arXiv subjects

Giacomo Oliveri

Publications and source records attributed to Giacomo Oliveri.

18 recordsLinked to original sources

arXiv2025

Multi-Functional Polarization-Based Coverage Control through Static Passive EMSs

An innovative multi-functional static-passive electromagnetic skin (SP-EMS) solution is proposed to simultaneously support, in reflection, two independent wave-manipulation functionalities with a single meta-atoms arrangement on the EMS aperture when illuminated by two EM sources operating at the same frequency, but working in different polarization states. Towards this end, a simple reference meta-atom is designed first to enable an accurate and independent control of each polarization component of the local reflection tensor. Successively, the macro-scale synthesis of multi-polarization (MP) SP-EMSs (MP-SP-EMSs) is carried out by solving a global optimization problem where a cost function, which mathematically codes separate requirements for each polarization, is minimized with a customized version of the system-by-design (SbD) technique. Representative results from a set of numerical and experimental tests are reported to assess the feasibility of a multi-function EMS based on polarization diversity as well as the effectiveness and the robustness of the proposed method for the synthesis of MP-SP-EMSs.

eess.SY↗

arXiv2025

One-Time Programmable Passive Electromagnetic Skins

The implementation of simple, inexpensive, and mass-production-oriented solutions for smart electromagnetic environments (SEMEs) is dealt with by introducing the concept of "one-time programmable" electromagnetic skins (OTP-EMSs). The simultaneous achievement of modular fabrication, (one-time) configurable reflection properties, passive-static operation, and zero maintenance is yielded by integrating expendable components at the atomic level of EMSs. Towards this end, an OTP meta-atom structure is properly defined and optimized to build EMSs featuring the desired scenario-dependent EM wave manipulation functionalities. In order to illustrate the features as well as to point out the potentialities of OTP-EMSs, a representative set of analytical, numerical, and experimental results is reported by considering different apertures, illuminations, and EM wave manipulation requirements.

eess.SY↗

arXiv2025

Time-Modulated EM Skins for Integrated Sensing and Communications

An innovative solution, based on the exploitation of the harmonic beams generated by time-modulated electromagnetic skins (TM-EMSs), is proposed for the implementation of integrated sensing and communication (ISAC) functionalities in a Smart Electromagnetic Environment (SEME) scenario. More in detail, the field radiated by a user terminal, located at an unknown position, is assumed to illuminate a passive TM-EMS that, thanks to a suitable modulation of the local reflection coefficients at the meta-atom level of the EMS surface, simultaneously reflects towards a receiving base station (BS) a "sum" beam and a "difference" one at slightly different frequencies. By processing the received signals and exploiting monopulse radar tracking concepts, the BS both localizes the user terminal and, as a by-product, establishes a communication link with it by leveraging on the "sum" reflected beam. Towards this purpose, the arising harmonic beam control problem is reformulated as a global optimization one, which is successively solved by means of an evolutionary iterative approach to determine the desired TM-EMS modulation sequence. The results from selected numerical and experimental tests are reported to assess the effectiveness and the reliability of the proposed approach.

eess.SY↗

arXiv2024

Unconventional Array Design in the Autocorrelation Domain -- Isophoric 1D Thinning

The synthesis of thinned isophoric arrays (TIAs) radiating mask-constrained patterns is addressed. By leveraging on the recently-introduced formulation of the design of antenna arrays in the autocorrelation-domain (AD), the TIA synthesis is recast as the matching of a target autocorrelation function derived from the user-defined guidelines and objectives. By exploiting the autocorrelation invariance of cyclic binary sequences, the AD solution space is significantly reduced and it is efficiently sampled by means of a discrete hybrid optimization approach. Two possible implementations of the AD-based TIA formulation are discussed and assessed in a set of representative numerical examples concerned with both ideal and real radiators, which are full-wave modeled to account for the mutual coupling effects. Comparisons with traditional pattern-domain (PD) synthesis methods are also considered to point out the features and the advantages of AD-based approaches.

eess.SP↗

arXiv2024

Synthesis of Wide-Angle Scanning Arrays through Array Power Control

A new methodology for the synthesis of wide-angle scanning arrays is proposed. It is based on the formulation of the array design problem as a multi-objective one where, for each scan angle, both the radiated power density in the scan direction and the total reflected power are accounted for. A set of numerical results from full-wave simulated examples - dealing with different radiators, arrangements, frequencies, and number of elements - is reported to show the features of the proposed approach as well as to assess its potentialities.

eess.SY↗

arXiv2024

On the Improvement of the Performance of Inexpensive Electromagnetic Skins by means of an Inverse Source Design Approach

A new methodology for the improvement of the performance of inexpensive static passive electromagnetic skins (SP-EMSs) is presented. The proposed approach leverages on the non-uniqueness of the inverse source problem associated to the SP-EMS design by decomposing the induced surface current into pre-image (PI) and null-space (NS) components. Successively, the unknown EMS layout and NS expansion coefficients are determined by means of an alternate minimization of a suitable cost function. This latter quantifies the mismatch between the ideal surface current, which radiates the user-defined target field, and that actually induced on the EMS layout. Results from a representative set of numerical experiments, concerned with the design of EMSs reflecting pencil-beam as well as contoured target patterns, are reported to assess the feasibility and the effectiveness of the proposed method in improving the performance of inexpensive EMS realizations. The measurements on an EMS prototype, featuring a conductive ink pattern printed on a standard paper substrate, are also shown to prove the reliability of the synthesis process.

eess.SY↗

arXiv2024

Optically-Transparent EM Skins for Outdoor-to-Indoor mm-Wave Wireless Communications

Optically-transparent opportunistic electromagnetic skins (OTO-EMSs) are proposed to enable outdoor-to-indoor (O2I) millimiter-wave (mmW) wireless communications with existing windows/glass-panels. More in detail, static passive EMSs consisting of optically-transparent conducting patterned layers attached to standard glass-panels are designed. Towards this end, both the phase coverage and the optical transparency of a meshed copper-based meta-atom printed on a non-dedicated insulated glass substrate are optimized. Successively, the feasibility of OTO-EMSs able to support mmW high-efficiency O2I transmissions along non-Snell refraction directions is numerically demonstrated.

eess.SP↗

arXiv2023

Memory-Enhanced Dynamic Evolutionary Control of Reconfigurable Intelligent Surfaces

An innovative evolutionary method for the dynamic control of reconfigurable intelligent surfaces (RISs) is proposed. It leverages, on the one hand, on the exploration capabilities of evolutionary strategies and their effectiveness in dealing with large-scale discrete optimization problems and, on the other hand, on the implementation of memory-enhanced search mechanisms to exploit the time/space correlation of communication environments. Without modifying the base station (BS) beamforming strategy and using an accurate description of the meta-atom response to faithfully account for the micro-scale EM interactions, the RIS control (RISC) algorithm maximizes the worst-case throughput across all users without requiring that the Green's partial matrices, from the BS to the RIS and from the RIS to the users, be (separately) known/measured. Representative numerical examples are reported to illustrate the features and to assess the potentialities of the proposed approach for the RISC.

eess.SY↗

arXiv2023

Reconfigurable and Static EM Skins on Vehicles for Localization

Electromagnetic skins (EMSs) have been recently considered as a booster for wireless sensing, but their usage on mobile targets is relatively novel and could be of interest when the target reflectivity can/must be increased to improve its detection or the estimation of parameters. In particular, when illuminated by a wide-bandwidth signal (e.g., from a radar operating at millimeter waves), vehicles behave like \textit{extended targets}, since multiple parts of the vehicle's body effectively contribute to the back-scattering. Moreover, in some cases perspective deformations challenge the correct localization of the vehicle. To address these issues, we propose lodging EMSs on vehicles' roof to act as high-reflectivity planar retro-reflectors toward the sensing terminal. The advantage is twofold: \textit{(i)} by introducing a compact high-reflectivity structure on the target, we make vehicles behave like \textit{point targets}, avoiding perspective deformations and related ranging biases and \textit{(ii)} we increase the reflectivity the vehicle, improving localization performance. We detail the EMS design from the system-level to the full-wave-level considering both reconfigurable intelligent surfaces (RIS) and cost-effective static passive electromagnetic skins (SP-EMSs). Localization performance of the EMS-aided sensing system is also assessed by Cramér-Rao bound analysis in both narrowband and spatially wideband operating conditions.

eess.SP↗

arXiv2022

Multi-Scaling Differential Contraction Integral Method for Inverse Scattering Problems with Inhomogeneous Media

Practical applications of microwave imaging often require the solution of inverse scattering problems with inhomogeneous backgrounds. Towards this end, a novel inversion strategy, which combines the multi-scaling (MS) regularization scheme and the Difference Contraction Integral Equation (DCIE) formulation, is proposed. Such an integrated approach mitigates the non-linearity and the ill-posedness of the problem to obtain reliable high-resolution reconstructions of the unknown scattering profiles. The arising algorithmic implementation, denoted as MS-DCIE, does not require the computation of the Green's function of the inhomogeneous background, thus it provides an efficient and effective way to deal with complex scenarios. The performance of the MS-DCIE are assessed by means of numerical and experimental tests, in comparison with competitive state-of-the-art inversion strategies, as well.

eess.SP↗

arXiv2022

Features and Potentialities of Static Passive EM Skins for NLOS Specular Wireless Links

The ability of passive flat patterned electromagnetic skins (EMSs) to overcome the asymptotic limit of the total path attenuation (TPA) of flat metallic reflectors of arbitrary size in non-line-of-sight (NLOS) specular wireless links is assessed. Closed-form expressions for the achievable TPA in EMS-powered NLOS links as well as the condition on the panel size of EMS-screens to improve the performance of flat passive conductive screens (PCSs) with the same aperture are derived and numerically validated by considering different incidence angles, screen apertures, transmitter/receiver distances, antenna gains, meta-atom geometries, and carrier frequencies.

eess.SY↗

arXiv2022

Generalized Analysis and Unified Design of EM Skins

A generalized formulation is derived for the analysis of the field manipulation properties of electromagnetic skins (EMSs) in the working regimes of interest for wireless communications. Based on such a theoretical framework, a unified method for the design of anomalous-reflecting and focusing EMSs is presented. Representative results, from a wide set of numerical experiments, are reported and validated with full-wave HFSS simulations to give the interested readers some insights on the accuracy, the effectiveness, and the computational efficiency of the proposed analysis/synthesis tools.

eess.SY↗

arXiv2021

On the Design of Modular Reflecting EM Skins for Enhanced Urban Wireless Coverage

The design of modular, passive, and static artificial metasurfaces to be used as electromagnetic skins (EMSs) of buildings for improving the coverage in urban millimeter-wave communication scenarios is addressed. Towards this end, an ad-hoc design strategy is presented to determine optimal trade-off implementative solutions that assure a suitable coverage of the areas of interest, where the signal from the base station is too weak, with the minimum complexity. More specifically, the admissible surface in the building facade is first partitioned into tiles, which are the minimum-size elements of the artificial coating (i.e., the building block of an EMS). Then, the search for the optimal EMS layout (i.e., the minimum number and the positions of the tiles to be installed) is carried out with a binary multi-objective optimization method. Representative numerical results are reported and discussed to point out the features and the potentialities of the EMS solution in the smart electromagnetic environment (SEME) as well as the effectiveness of the proposed design method.

eess.SY↗

arXiv2021

Building a Smart EM Environment -- AI-Enhanced Aperiodic Micro-Scale Design of Passive EM Skins

An innovative process for the design of static passive smart skins (SPSSs) is proposed to take into account, within the synthesis, the electromagnetic (EM) interactions due to their finite (macro-level) size and aperiodic (micro-scale) layouts. Such an approach leverages on the combination of an inverse source (IS) formulation, to define the SPSS surface currents, and of an instance of the System-by-Design paradigm, to synthesize the unit cell (UC) descriptors suitable for supporting these currents. As for this latter step, an enhanced Artificial Intelligence (IA)-based digital twin (DT) is built to efficiently and reliably predict the relationships among the UCs and the non-uniform coupling effects arising when the UCs are irregularly assembled to build the corresponding SPSS. Towards this end and unlike state-of-the-art approaches, an aperiodic finite small-scale model of the SPSS is derived to generate the training database for the DT implementation. A set of representative numerical experiments, dealing with different radiation objectives and smart skin apertures, is reported to assess the reliability of the conceived design process and to illustrate the radiation features of the resulting layouts, validated with accurate full-wave simulations, as well.

eess.SY↗

arXiv2021

Planning of EM Skins for Improved Quality-of-Service in Urban Areas

The optimal planning of electromagnetic skins (EMSs) installed on the building facades to enhance the received signal strength, thus the wireless coverage and/or the quality-of-service (QoS) in large-scale urban areas, is addressed. More specifically, a novel instance of the System-by-Design (SbD) paradigm is proposed towards the implementation of a smart electromagnetic environment (SEME) where low-cost passive static reflective skins are deployed to enhance the level of the power received within selected regions-of-interest (RoIs). Thanks to the ad-hoc customization of the SbD functional blocks, which includes the exploitation of a digital twin (DT) for the accurate yet fast assessment of the wireless coverage condition, effective solutions are yielded. Numerical results, dealing with real-world test-beds, are shown to assess the capabilities, the potentialities, and the current limitations of the proposed EMSs planning strategy.

eess.SY↗

arXiv2021

On the Use of Nonlinear Metasurfaces for Circumventing Fundamental Limits of Mantle Cloaking for Antennas

The aim of this communication is to investigate and demonstrate the possibility to overcome the fundamental limitations of mantle cloaking for antennas by exploiting nonlinear metasurfaces. First, we recap and give additional physical insights about the fundamental bounds that apply to the electric properties of an antenna that is made invisible at its own resonance frequency. Then, an innovative strategy is proposed to circumvent these limits through the introduction of nonlinear elements that are able to dynamically transform the geometry of the cloaking metasurface depending on the power level of the impinging field. Different nonlinear designs are discussed, and their effectiveness is assessed through the relevant benchmark example of a half-wavelength dipole antenna able to efficiently transmit high-power signals while being invisible to low-power ones. In addition, the capability of such nonlinear mantle cloaks to enable the shaping of the radiation pattern of an antenna array depending on the power level of the received/transmitted signal is demonstrated. These innovative cloaking devices may find applications in different radiating systems enabling unprecedented functionalities.

physics.app-ph↗

arXiv2021

Antenna Array Thinning Through Quantum Computing

Thinning antenna arrays through quantum Fourier transform (QFT) is proposed. Given the lattice of the candidate locations for the array elements, the problem of selecting which antenna location has to be either occupied or not by an array element is formulated in the quantum computing (QC) framework and then addressed with an ad-hoc design method based on a suitable implementation of the QFT algorithm. Representative numerical results are presented and discussed to point out the features and the advantages of the proposed QC-based thinning technique.

quant-ph↗

arXiv2021

Holographic Smart EM Skins for Advanced Beam Power Shaping in Next Generation Wireless Environments

An innovative approach for the synthesis of inexpensive holographic smart electromagnetic (EM) skins with advanced beamforming features is proposed. The complex multiscale smart skin design is formulated within the Generalized Sheet Transition Condition (GSTC) framework as a combination of a mask-constrained isophoric inverse source problem and a micro-scale susceptibility dyadic optimization. The solution strategy integrates a local search procedure based on the iterative projection technique (IPT) and a System-by-Design (SbD)-based optimization loop for the identification of optimal metasurface descriptors matching the desired surface currents. The performance and the efficiency of the proposed approach are assessed in a set of representative test cases concerned with different smart skin apertures and target pattern masks.

eess.SY↗