Diffuse field cross-correlation in reverberation chambers – DICOREV
The purpose of the DICOREV project is to pave the way for a new technique to characterize electromagnetic antennas and scattering objects in reverberation chambers. Recent advances in wireless communications, radar imaging, monitoring or multi-parameter sensing have made the characterization of systems equipped with radio-frequency antennas highly challenging. For instance, arrays of ultra-wideband antennas of MIMO (multiple input-multiple output) and massive MIMO systems are becoming increasingly large, especially for millimeter-wave 5G communication systems. Miniaturized and embedded antennas distributed in any piece of equipment are also involved in the context of the internet of things where they are associated to sensors transmitting various types of data. Those systems therefore require developing new characterization techniques to measure the associated communication rate, control their in situ performance and maintain their efficiency. The need of Radar Cross-Section (RCS) measurement has also strongly increased in recent years due to the development of radars for civil applications, for transportation systems.
Here, we exploit the cross-correlation of the diffuse field generated by sources in a chaotic reverberation chamber to passively retrieve the impulse response between receiving antennas both in the centimeter- and millimeter-wave ranges. Mode-stirred reverberation chambers (RC) are now used as an alternative solution to anechoic rooms to measure antenna performance such as the efficiency, the sensitivity or the diversity gain for multiple antennas. Instead of mimicking free-space propagation, the field generated within an RC is naturally diffuse so that receiving antennas are illuminated by random plane waves. The consortium that gathers leading experts in the fields of noise correlation, wave chaos and reverberation chambers will progressively acquire theoretical and experimental knowledge of the specific properties of electromagnetic cross-correlation in RCs. Even though it has led to spectacular results in seismology, the ambient noise Green’s function retrieval method still remains largely unexplored in electromagnetism.
We will provide a theoretical framework that can be exploited for a quantitative analysis of the cross-correlation function. This will be achieved by taking advantage of the universality of the field statistics within a chaotic cavity. The statistical properties of the RC and the distribution of noise sources ensuring the convergence of the cross-correlation toward the impulse response will be extracted and verified numerically and experimentally. The extraction of the coupling between two antennas will be investigated and demonstrated using different kinds of noise sources ranging from ambient thermal radiations to perfectly controlled sources. The performance of the proposed technique will be compared to usual active measurements in an anechoic room for well-known antennas as a proof-of-concept.
The cross-correlation technique will overcome current limitations of coupling measurements between two receiving antennas which do not have the possibility to be turned into their emitting modes. It will then be extended to multiple input-multiple output systems and will provide a great simplification of the setup to measure the mutual coupling matrix of an antenna array which controls the performance of MIMO communication and radar imaging systems. Finally, it will be used to extract the radiation pattern of miniaturized and integrated antennas by recording the cross-correlation function on a set of sensors in the vicinity of the device under-test. This contactless approach is crucial because cables strongly disturb the radiation patterns of those antennas. Retrieving scattering pattern of objects for RCS measurements will also be explored especially in the case of extended objects-under-test.
Monsieur Matthieu DAVY (Institut d'Electronique et de Télécommunications de Rennes)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
IL Institut Langevin Ondes et Images
ESYCOM laboratoire d'Electronique, Systèmes de Communications et Microsystèmes
IETR Institut d'Electronique et de Télécommunications de Rennes
CNRS DR20__INPHYNI Centre National de la Recherche Scientifique Délégation Côte d'Azur_Institut de physique de Nice
Help of the ANR 299,960 euros
Beginning and duration of the scientific project: December 2017 - 36 Months