Statistics of the electromagnetic response of a chaotic reverberation chamber

This article presents a study of the electromagnetic response of a chaotic reverberation chamber (RC) in the presence of losses. By means of simulations and of experiments, the fluctuations in the maxima of the field obtained in a conventional mode-stirred RC are compared with those in a chaotic RC in the neighborhood of the Lowest Useable Frequency (LUF). The present work illustrates that the universal spectral and spatial statistical properties of chaotic RCs allow to meet more adequately the criteria required by the Standard IEC 61000-4-21 to perform tests of electromagnetic compatibility.Comment: 6 pages, 9 figure

Experimental width shift distribution: A test of nonorthogonality for local and global perturbations

The change of resonance widths in an open system under a perturbation of its interior has been recently introduced by Fyodorov and Savin [Phys. Rev. Lett. 108, 184101 (2012)] as a sensitive indicator of the nonorthogonality of resonance states. We experimentally study universal statistics of this quantity in weakly open two-dimensional microwave cavities and reverberation chambers realizing scalar and electromagnetic vector fields, respectively. We consider global as well as local perturbations, and also extend the theory to treat the latter case. The influence of the perturbation type on the width shift distribution is more pronounced for many-channel systems. We compare the theory to experimental results for one and two attached antennas and to numerical simulations with higher channel numbers, observing a good agreement in all cases

Diffuse field cross-correlations: Scattering theory and electromagnetic experiments

The passive estimation of impulse responses from ambient noise correlations arouses increasing interest in seismology, acoustics, optics and electromagnetism. Assuming the equipartition of the noise field, the cross-correlation function measured with non-invasive receiving probes converges towards the difference of the causal and anti-causal Green’s functions. Here, we consider the case when the receiving field probes are antennas which are well coupled to a complex medium – a scenario of practical relevance in electromagnetism. We propose a general approach based on the scattering matrix formalism to explore the convergence of the cross-correlation function. The analytically derived theoretical results for chaotic systems are confirmed in microwave measurements within a mode-stirred reverberation chamber. This study provides new fundamental insights into the Green’s function retrieval technique and paves the way for a new technique to characterize electromagnetic antennas.French Agence Nationale de la Recherche (reference ANR-17- ASTR-0017); European Union (European Regional Development Fund (ERDF)), French region of Brittany and Rennes Métropole (CPER Project SOPHIE/STIC & Ondes); Institut Universitaire de France (IUF)

Low-Loss microstrip MEMS technology for RF passive components

A new low loss and low cost microstrip MEMS technology is presented. Two inverted microstrip lines, one on low loss silicon and the other on glass have been measured and simulated. A good concordance of the results has been obtained. Simulations have been used to study the influence of several parameters, and the results of simulations allow us to adjust the lines dimensions to prescribed characteristics

Optical properties characterization of silicon micro/nanostructures: Towards a predictive reflectance simulation model based on surface topography

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Modeling of Inverted Coupled Microstrip Lines Fabricated using MEMS Technology

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Hollow Cylinder Radar Cross-Section Pattern Measurement in a Reverberation Chamber

International audienceIn this communication, radar cross-section (RCS) measurements of a hollow cylinder are performed within a reverberation chamber and the extracted RCS is compared to the one obtained through anechoic chamber measurements and CST studio simulations. The satisfying agreement between the three approaches shows accurate RCS characterization can be obtained in RC

Radar Cross-Section Pattern Measurement of a Complex Target in Reverberation Chamber

International audienceRadar cross-section (RCS) measurements using reverberation chambers (RCs) have been recently introduced and improved firstly for estimating the most important scattering directions before being able to also retrieve the RCS level. In this communication, this method is extended to the RCS measurement of a complex target. Measurement results in both HH and VV polarizations are shown to be very consistent with simulation results using CST Studio Suite. Furthermore, the distance of the main scattering areas according to the azimuth angle is reported. © 2023 European Microwave Association (EuMA)

Effects of Doping on the Morphology and Infrared Radiative Properties of Black Silicon

International audienceFor the first time, we show that the density of nanostructures on Black Silicon obtained by wafer-level cryogenic plasma processing increases with a high level of doping, extending the spectral range of its very high absorptivity from near-infrared to far-infrared. We have found experimentally and confirmed by simulations that, for highly doped Black Silicon, a high absorptivity is observed till 15 µm. Subsequent processing of SEM images reveals that these noteworthy radiative properties are probably due to particular morphological features of heavily doped Black Silicon at the nano-scale. These features are quantified through statistical image processing. Reported results pave the way to highly integrated and effective infrared sources using Black Silicon