The plane wave diffraction by a slit in a material screen is analyzed using the Wiener-Hopf technique together with generalized boundary conditions (GBC). Exact and high-frequency asymptotic solutions are obtained. The scattered field is evaluated asymptotically based on the saddle point method and a far field expression is derived. Numerical examples on the far field intensity are presented and the scattering characteristics of the slit are discussed.
Very few designs are reported in the terahertz range for realizing dynamic beam-steering of the antenna radiation pattern at a fixed frequency. In this work, we propose a one-dimensional leaky-wave antenna based on nematic liquid crystals (NLC). More specifically, an NLC cell is sandwiched between two foam layers, the top one patterned with a partially reflecting sheet (PRS), and the bottom one entirely metalized to have a ground plane. Two lateral perfect magnetic conductor walls allow for a dominant TM leaky mode propagating in the structure. The beam is then steered by applying a low-frequency driving voltage through the ground and the PRS. The trade-off among radiation efficiency, angular steering range, and gain that commonly affects any reconfigurable antenna is properly handled through a suitable choice of the design parameters. Full-wave results are finally provided to demonstrate the concept.
Vehicle-to-Everything (V2X) is an emergent technology for enhancing traffic efficiency, road safety and autonomous driving. Vehicles interconnected with their prevalent wireless environment are prone to various security threats that might affect traffic and life safety immensely. Jamming attacks, a legacy and dated problem, still persists much to the havoc of V2X communications. The following paper proposes a framework for jammer detection adapted to V2X communications scenario. A Generalized Dynamic Bayesian network is used to learn the V2X signal environment in a statistical manner. Subsequently, a Modified Markov Jump Particle filter (M-MJPF) is used for signal predictions where the innovations in the observed signal versus the predicted signal enable our framework to detect the jammer. Simulation results highlight the efficacy and accuracy of our approach in V2X jammer detection.
This report presents a recently developed fabrication method combining fused deposition modelling with Field's metal for the manufacturing of complex metal structures. First, a dielectric mold is printed using standard 3D printing methods. The mold is designed with hollow cavities, which form the desired shape of the structure's metal parts. Next, molten Field's metal is injected inside, filling the cavities and adopting their architecture. Field's metal has a low melting point of 65 degrees Celsius, which can realistically be lower than the temperature where heat deformation in numerous thermoplastic materials occurs. This method can produce metamaterial resonators with high quality factors. Numerical methods are used to model the response of the metamaterial and further investigate the resonance.
The principal element of interest concerning the use of Synthetic Aperture Radar (SAR) technology in the automotive scenario is the possibility to synthesize an arbitrarily long array by exploiting the natural motion of the ego-vehicle, and therefore achieve much finer spatial resolution and improved detection capabilities without increasing hardware requirements in terms of number of physical antennas. In this paper, we discuss the application of SAR imaging in the automotive context under a theoretical and experimental perspective. Experimental results are shown based on open road campaign data acquired using an 8-channel Radar at 77 GHz, considering the cases of side-looking SAR, forward SAR, and SAR imaging of moving targets. Results corroborate the idea that SAR imaging could be successfully and systematically used in the near future for high-resolution mapping of the urban environment.
