Programa del congreso

We demonstrate that a waveguide consisting of a Pair of Parallel Curved Conducting Surfaces can be used as an analogous electromagnetic model of the gravitational field generated by a Schwarzschild black hole. The influence of gravity on the propagation of electromagnetic waves is encoded in the curvature of the surfaces of the waveguide. The results obtained for the propagation of a one-dimensional Gaussian Beam by full-wave simulations show excellent agreement with the Schwarzschild geodesic structure. To the best of our knowledge, we highlight that this is the first time that an analogous electromagnetic model, based on this type of waveguide, has been proposed to reproduce the electromagnetic wave propagation within the gravitational field of a Schwarzschild black hole. This approach can be advantageously employed by the whole astrophysical community as a means to better inquire the propagation of electromagnetic waves inside the Schwarzschild gravitational field, as well as their interactions.

This contribution presents a compact multi-faceted reflectarray in a Cassegrain configuration. The reflectarray surface is comprised of five identical panels arranged edge to edge following a cylindrical parabolic profile. The antenna provides dual-linear polarization (LP) and it operates in Ka-band, generating a broadside beam pattern. The performance of this antenna is assessed and compared with two alternative approaches: a single-facet reflectarray and a multi-faceted structure with three identical panels. The proposed multi-faceted structure achieves the best in-band performance, with a 60% enhancement in the gain–bandwidth product compared to the single-facet case and a 10% improvement compared to the multi-faceted approach based on three panels.

Microwave Imaging (MWI) is a promising technology that deals with scenarios where the imaging target is unreachable directly, optically obscure, and presents an unknown electrical contrast at the microwave band, situations illustrated by medical applications such as the imaging of breast cancer, brain stroke, or bone fractures, or in the industrial context where it is used for detecting food contaminants. It exploits the advantages of working at microwaves, reducing measuring times, cost, and dimensions of the imaging devices, complementing standard gold technologies like Magnetic Resonant Imaging (MRI), X-rays, or CT scans, albeit with a lower spatial resolution. MWI represents an inverse problem aiming to retrieve the EM properties from the scattered fields. It is a non-linear and ill-posed imposed by the loss of information because the unknown is not directly measured and instead assessed using its footprint in the measured scatted fields, usually gathered by an array of antennas outside of DoI. Thus, the problem is regularized, adding a-priori information related to the problem’s physics through analytical models or high-fidelity simulations that provides the electric fields employed to build the imaging operator. Depending on the application and the system antenna distribution, i.e., rings, conformal shape, and tunnel shape, the imaging operator presents a non-uniform Point Spread Function (PSF). So, the retrieved contrast of an ideal point-like contrast presents a non-symmetrical 3-D spatial, which conveys an issue in the shape spatial representation of the imaged target. For example, this is the primordial importance in the medical application where the physicians look for the actual shape and dimension of a pathology evolving. To deal with this limitation, this contribution proposes a scheme that enhances the intrinsic features of the image retrieval, applying an optimization-based weighting of the singular value decomposition of a discretized operator guided by shape factor symmetry. As a result, a non-uniform PSF is morphed and shaped into a more uniform one, improving shape retrieval. The scheme is tested numerically and experimentally using an MWI system for brain stroke imaging, while realistic morphologically mimicked targets are used.

Anticipating the detection of Parkinson's Disease is critical to delay its effects. This paper presents the design of a radar network for the early-detection of Parkinson's Disease analyzing gait impairments. The preliminary results of the radar network show that gait biometrics, and gait asymmetries linked to Parkinson's Disease can be clearly identified in the micro-Doppler signature.

This paper presents a study on periodic structures based on glide symmetric holes for the design of layered waveguides at high frequencies (W-band) avoiding power leakage and allowing to achieve micrometer accuracies with a low cost and ease of fabrication compared to other techniques such as gap waveguide technology. A linear array of slots in a resonant multi-layer waveguide has been designed and manufactured to experimentally validate the proposed technology. A deep analysis of the prototypes has been performed by measuring S-parameters, directivity, gain, antenna dimensions and roughness of the materials. Furthermore, the repeatability of the manufacturing process has been studied. Good results have been obtained for the antenna electrical parameters, consistent with the simulations, and the fabrication process has been determined to be accurate.

In this contribution a planar circularly polarized array with a corporate feeding network in waveguide technology is presented. The antenna comprises three layers: the radiating array and a two-stage feeding network. Due to the complex multilayer design of the antenna, manufacturing a prototype is challenging, particularly at higher frequencies where power leakage between the layers may occur. This paper examines several manufacturing techniques and design strategies to determine their suitability for implementing such intricate antenna structures. The array under evaluation is designed for applications in the lower end of the millimeter band, specifically in Ka band (38 GHz), where a 5G satellite expansion is bound to happen.