This study presents a comprehensive full-wave numerical dosimetry approach for large-scale rodent bioassays in Reverberation Chambers (RCs), improving upon prior methods that rely on idealized Plane Wave (PW) superposition. A "digital twin" of the Universit & agrave; Politecnica delle Marche RC was implemented using Transmission-Line Matrix and Finite Element Method solvers to characterize exposure homogeneity across rodent cages at 900 MHz. Unlike PW-superposition models, loaded-RC simulations account for realistic experimental constraints, such as intruding water-supply metal piping, specific antenna designs and placements, and actual mode stirrers. The loaded-RC electromagnetic characteristics were investigated by analyzing the field impedance ratios, yielding discrimination criteria for the probe location and type. Cage-wise instantaneous and ensemble-averaged whole-body specific absorption rate (wbSAR) distributions were evaluated using postured homogeneous rat models. Furthermore, investigations into exposure imbalance mitigation strategies demonstrated significant benefits when spinning cage assemblies. An analysis of mass-dependent exposures revealed a notably weaker correlation between body mass and wbSAR, as well as a much larger wbSAR cage dependence, compared to earlier PW-based predictions, further highlighting the necessity of realistic RC modeling for reliable rodent bioassay exposure design.

In this work, we present ferroelectric metal-insulator-metal (MIM) diodes based on a 7 nm-thick zirconium oxide layer, deposited between two dissimilar electrodes (i.e., platinum and titanium/gold). Owing to the small contact areas (no greater than $4 \times 4 \mu \mathrm{m}^{2})$, the fabricated diodes exhibit a cutoff frequency surpassing 173 GHz. Ab initio investigations allowed to predict very accurately the measured DC current-voltage curves, the agreement between simulations and experiments being impressive, thus validating the quantum transport mechanism in macroscopic devices. Further, a rigorous circuit model has been developed through DC and RF measurements, and the voltage responsivity has been evaluated at different frequencies and input power levels. In the absence of any matching network, the standalone MIM diodes exhibit a record responsivity of almost $11,200 \mathrm{V} / \mathrm{W}$ at $\mathbf{2. 4 5 ~ G H z}$.

This paper presents a tool that integrates an electromagnetic model based on physical optics (PO) for evaluating the reflection of large object, with a tool developed in a previous paper for characterizing the scattering characteristics of small and complex target. The aim is to provide a model for characterizing the interaction of the target with the surrounding environment. The model is fast and permits us to separate the contribution to the scattering characteristics of the target, due to the target itself and to the interaction with the external environment.

Reverberation chambers play a fundamental role in evaluating the efficacy of wireless communication systems by providing controlled environments for testing. One crucial aspect of this assessment is the manipulation of the Rician K factor within these chambers. The inherent challenge lies in the typically low values of the Rician K factor, necessitating intentional adjustments to replicate real-world communication scenarios accurately. This paper aims to expound upon the statistical analysis of the Rician K factor, focusing on the various measures undertaken to modulate this parameter. The experimentation involves a comprehensive examination of actions taken to tune the Rician K factor. One of the key strategies involves the strategic insertion of lossy elements within the reverberation chamber. These elements introduce intentional signal attenuation, impacting the Rician K factor and contributing to a more realistic simulation of wireless communication conditions. The paper delves into the intricacies of selecting and placing these lossy elements to achieve the desired level of signal degradation and, consequently, an appropriate Rician K factor. Furthermore, the investigation considers the positioning of these lossy elements within the reverberation chamber. The spatial distribution and arrangement of these elements can significantly influence the electromagnetic field characteristics, affecting the Rician K factor. In addition to the insertion and placement of lossy elements, the orientation of the receiver within the chamber emerges as another factor under analysis. The paper explores how variations in receiver orientation impact the statistics of the Rician K factor

In this work, we present a metal-insulator-metal (MIM) diode, based on quantum tunnelling phenomena. Its model is based on a multilevel modelling approach consisting of atomistic and continuum simulations, fully validated by extensive measurements. The MIM structure comprises a hafnium oxide (or hafnia, HfO2) dielectric layer, less than 4 nm thick and a square contact area of only 4 mu m2, placed between two metallic electrodes, namely platinum as the source and titanium as the drain. The current-voltage (I-V) curve has been estimated by Density Functional Theory (DFT) calculations through an optimisation of the interfaces between metals and monoclinic HfO2. The dielectric parameters arising from ab initio computations have then been used as inputs for the successive circuit and electromagnetic simulations. Finally, the multilevel model has been validated with great accuracy, first measuring the I-V characteristics by applying a drain-source voltage between -1 V and +1 V, and then extracting the scattering parameters up to 40 GHz, thus demonstrating that DFT and circuit/electromagnetic simulations match almost perfectly the experimental ones. These outcomes represent the first study of such nanoscale devices investigated by means of a rigorous atomistic-to-continuum approach, providing invaluable information in order to improve fabrication and correctly assess the macroscale performance of nanoelectronics systems.

In this work, a simple and efficient circuit modeling of metamaterial structures, providing a compact circuit able to describe accurately the device over a large bandwidth of operation, is proposed. The equivalent circuit model is obtained by the identification process of the load in terms of shunt branches constituted by reactive elements that can be both positive and negative. The circuit model is validated by analyzing the split-ring resonator (SRR) structure. The presence of negative elements in the non-Foster load is transformed into positive reactive elements by converting the load from shunt into series. Unlike the T or $\Pi $ circuit models, using this approach a circuit model can be constructed directly from the scattering parameters and valid for any circuit topologies.

In this paper, we propose a comparative method to analyze a complex microwave structure consisting of a silicon-based coplanar waveguide line and four electric-LC resonators, thus forming a wideband microwave band-stop filter that can be easily integrated at the wafer level together with other devices and sub-systems for large-scale production of high-frequency electronics. A rigorous and careful approach is needed when choosing the proper simulation settings and, as a good rule of thumb, both time and frequency domains should provide the same results. Furthermore, the experimental validation requires supplementary components (like connectors), often ignored when designing an electromagnetic structure highly impacting on the overall performance. In this work, we go in depth into all these issues and show how the right choices in terms of computational parameters can lead to a good agreement with the measurements of the proposed CMOS-compatible band-stop filter in the band 2–18 GHz, with a relative bandwidth of almost 30 % around the band-stop frequency of 13.2 GHz and a rejection level of − 40 dB.

This article presents a new computational approach that allows rapid analysis of the electro-magnetic scattering (EMS) characteristics of static or moving complex radar targets. The scattering features of the object are represented through a generalized scattering matrix H, whose elements can be measured or computed using conventional numerical techniques, for example, CST software in the proposed case, and considering prescribed sampled directions. A cardinal series then is adopted to reconstruct the complete scattering pattern by suitably extending the approach to calculate the target’s scattering matrix for any incidence wave and any observation point. The number of finite samples, that is, the dimension of the scattering matrix depends only on the maximum dimension of the target. A PEC sphere and a PEC 3-D complex object have been analyzed in detail. Precise, fast, and stable sampling algorithms have been applied to these targets in the static case and in motion. In particular, the field scattered by the moving objects is then used to carry out the micro-Doppler analysis of the object radar signature.

This paper presents a novel algorithm to emulate the Rician K-factor of a wireless communication environment using a reverberation chamber. In particular, it was focused on the frequency bands used by 5G technology for data transmission. Unlike the current state of the art, the increase of the Rician K-factor is not achieved by inserting lossy material in the chamber, but through the proposed algorithm, which selects a subset of electromagnetic field realizations inside the chamber. The algorithm was first applied to the results of a simulation obtained by using an analytical model that predicts the main physical quantities inside a rectangular cavity where a multiple monopole source stirring action is implemented. Subsequently, the robustness of the algorithm and its applicability was tested on a set of data retrieved from experimental measurements. In all of the considered scenarios, the validity of the proposed method was demonstrated.

This paper describes a novel method to reconstruct the radiated emission of a device under test placed in a reverberation chamber equipped with multiple monopole source stirring technique. The method is based on the measurement of the normal component of the electric field, collected close to the walls of the chamber by the monopole antennas. The main improvement from the previous formulation of the method is that the only knowledge of the amplitude of the electric field is sufficient to reconstruct, within a predictable range of uncertainty, the maximum level of the radiation of the device over all the directions at a given distance. The consequent advantage is that the method is immediately usable in a realistic scenario for emission tests, where an EMI receiver or a spectrum analyzer are used to measure the electric field and therefore only the amplitude of the field is retrieved.

Reverberation chambers usually exhibit low values of the Rician k factor; this means that the stirred component of the electromagnetic field is dominant with respect to the unstirred one. To increase this parameter in order to emulate propagation environments for 5G telecommunication systems, usually lossy elements are added into the chamber. In this way, the strength of the field inside the cavity decreases and more amplification of the signal is needed. This paper shows how to increase the Rician k factor by selecting a subset of electromagnetic configurations without the insertion of dissipative material. Successful results were obtained using different typologies of stirring techniques, multiple monopole source stirring, rotating paddles mechanical stirring, and oscillating wall stirring.

This paper details the extraction of two possible equivalent circuits over a wide band for an mm-Wave Electric-LC resonator on a multilayer stack, based on a T structure or on only one shunt susceptance with two transmission lines. An identification process applied to the frequency behavior of the reactance/susceptance is used to obtain a more appropriate and efficient equivalent circuit, giving a physical meaning, if any, to each inductance, capacitance or resonator tank contained in the proposed circuits.

This paper is based on the analytical formulation of a method for predicting the electromagnetic field radiated by a wire antenna placed in a reverberation chamber. The antenna is discretized by a series of oblique segments. After verifying this assumption using full-wave numerical simulations, the proposed model is applied to a broadband antenna designed for a multiple antenna source stirred reverberation standard. The model can be used to analyze the performance of the chamber with respect to a number of indicators. This analysis has been extended to the entire frequency range in which the chamber has been experimentally characterized

We analyze the measured reflection coefficient of antennas in unconventional multiple monopole source stirring reverberation chambers. The reverberation chamber that we used is equipped by stochastic diffractors that are used to break the geometrical symmetries of the baseline metallic cavity. The experimental measurements of the average reflection parameter show reduced frequency fluctuations over a broad frequency range. Furthermore, the average reflection coefficient measured in the reverberant environment is in good agreement with the measurement of the same antenna in free space conditions.

In this paper a novel antenna for an electromagnetic assistance system for autonomous walking of blind or visually impaired people is presented. Its main aim is to detect obstacles that the white cane is not able to intercept, in particular those that can hurt the head or thorax zone. The proposed antenna has a fan beam radiation pattern, works at 24 GHz, in a frequency band reserved for ISM (Industrial, Scientific and Medical) applications. The antenna is designed using a numerical electromagnetic tool and its capability to detect a wide set of obstacles was investigated through numerical simulations and experimental measurements. Results confirm the good performances of the antenna and its capability to extend by a few meters the region usually explored by the white cane.

This paper presents a general and quasi-analytical method aimed at reconstructing the electric field radiated by equipment under test (EUT), in free space through the knowledge of the values of the electric field sampled on the walls of a rectangular metallic enclosure. The algorithm is based on a set of equivalent magnetic and electric currents, regularly placed in a sub volume of the chamber, whose values are determined to reconstruct the electric field due to the EUT on the samples. Results show that the method is general because it can be applied to a wide set of EUTs, but it is also flexible because it is able to exploit some a priori knowledge of the source to improve its accuracy and efficiency.

This paper presents an optimization of a method to reconstruct the radiated emissions of an equipment under test by the measurement of the electric field samples collected on the walls of a reverberation chamber. This means that only the orthogonal component of the electric field is necessary to obtain the radiative behavior of the device in free space conditions. The use of the equivalence principle allows one to reduce the number of equivalent sources used to reconstruct the radiation of the device. In fact, in the previous version of the method, the sources are placed into the entirety of working volume of the reverberation chamber. In the current version of the method, only the surface surrounding the equipment under test is discretized. The analytical implementation of the method is proposed for a particular stirring action: the multiple monopole source stirring technique. This technique is based on an array of monopoles placed onto the walls of the cavity, and therefore no further hardware is needed for the reconstruction of the radiated emissions. The method is experimentally validated in a real scenario.

In this article, we present a fast and accurate numerical method for the computation of scattered electromagnetic field from targets of different sizes and complex shapes. The approach is based on the sampling representation of the complex reflection coefficient of the target where both amplitude and phase information are considered, rather than the usual radar cross section (RCS) where the phase information is missed. The scattering features of the target are organized in a 5-D complex matrix H calculated numerically. The electromagnetic tool (CST) computes this H matrix evaluating the scattered field in a finite number of selected directions. This number is chosen in order to obtain a good reconstruction of overall scattering feature. As assumed for the scattered field, matrix H is also calculated for the same discrete set of directions of the incident wave. Two numerical examples are provided to demonstrate the correctness and the efficiency of the proposed method.

This article reports on the experimental validation of a method to predict radiated emissions of equipment under test in a reverberation chamber where the multiple monopole sources stirring technique is implemented. The method is validated for three different case studies: a loop, a slot in a metal enclosure, and a realistic device comprised of the chassis of a power supply for a workstation. The reconstruction of the free space electromagnetic emissions starting from measurements in a reverberation chamber is compared with measurements in an anechoic environment. A statistical analysis of the uncertainty due to a positioning error of the field sample measurement points is also proposed.