Metasurface dome for above-the-horizon grating lobes reduction in 5G-NR systems

The use of fifth-generation (5G) new radio (NR) spectrum around 26 GHz is currently raising the quest on its compatibility with the well-established Earth exploration-satellite service, which may be blinded by the spurious radiation emitted above the horizon (AtH) by base station (BS) antennas. Indeed, AtH grating lobes are often present during cell scanning due to the large interelement spacing in BS array antennas for achieving higher gains with a reduced number of RF chains. In this letter, we propose an approach based on an electrically thin metasurface-based dome for the reduction of AtH grating lobes in 5G-NR BS antennas. The proposed scanning range shifting approach exploits the natural lower amplitude of the grating lobes when the antenna array scans in an angular region closer to the broadside direction. The grating lobe reduction is here demonstrated considering a 1x4 phased linear antenna array operating under dual-liner +/- 45 degrees-slant polarization. A simple design procedure for designing the metasurface dome is reported, together with the antenna performances, evaluated through a proper set of numerical experiments. It is shown that the grating lobe radiation toward the satellite region is significantly reduced, whereas the overall insertion loss is moderate

Guest Editorial Special Cluster on Functionalized Metasurface-Based Covers and Unconventional Domes for Dynamic Antenna Systems

The papers in this special section focus on recent advancements in this field and provide an overview of the potential applications of this technology in the next generation antenna devices, with emphasis on metamaterial-based enhancements enabling real-time control of their radiation characteristics

Maximizing Pencil-Beam Pattern Performance in Metasurface Antennas Through Full-Wave Optimization

We propose a design and optimization scheme for metasurface antennas that decouples the antenna and the feeding structure to maximize the antenna performance. This approach uses 2.5D fast algorithms to simulate the large antenna, significantly decreasing the amount of time and complexity required compared to 3D full-wave simulations. The optimization process is designed to maximize the antenna efficiency within a pencil beam pattern mask with a predefined database of unit cells. We present numerical results of the 3D metasurface antenna model comparing our code with a commercial solver to demonstrate the effectiveness of our approach

Enhancing the beam scanning capability of phased arrays using quadratic-gradient metasurface dome

In this contribution, we propose a quadratic-gradient metasurface dome operating in the near-field region of a dual-polarized phased array able enhancing its grating-lobe-free scanning range without affecting its other characteristics. The dome consists of an array of Huygens unit-cells exhibiting an extremely low insertion loss and a proper phase shift in transmission. The main characteristic of the proposed dome is the quadratic-gradient phase profile, which minimizes the beam divergence in broadside direction, whereas linearly increases the scanning region in off-broadside pointing angles. A proper set of numerical simulations have been performed showing the capability of the proposed dome to enhance the grating lobe free scanning region from -58° to -83°

rKv1.2 overexpression in the central medial thalamic area decreases caffeine-induced arousal

The voltage-gated potassium channel Kv1.2 belongs to the shaker-related family and has recently been implicated in the control of sleep profile on the basis of clinical and experimental evidence in rodents. To further investigate whether increasing Kv1.2 activity would promote sleep occurrence in rats, we developed an adeno-associated viral vector that induces overexpression of rat Kv1.2 protein. The viral vector was first evaluated in vitro for its ability to overexpress rat Kv1.2 protein and to produce functional currents in infected U2OS cells. Next, the adeno-associated Kv1.2 vector was injected stereotaxically into the central medial thalamic area of rats and overexpression of Kv1.2 was showed by in situ hybridization, ex vivo electrophysiology and immunohistochemistry. Finally, the functional effect of Kv1.2 overexpression on sleep facilitation was investigated using telemetry system under normal conditions and following administration of the arousing agent caffeine, during the light phase. While no differences in sleep profile were observed between the control and the treated animals under normal conditions, a decrease in the pro-arousal effect of caffeine was seen only in the animals injected with the adeno-associated virus-Kv1.2 vector. Overall, our data further support a role of the Kv1.2 channel in the control of sleep profile, particularly under conditions of sleep disturbance

Line-wave waveguides: design procedure and performance comparison

Line waves are one-dimensional (1D) interface modes excited at the discontinuity between two reactive sheets of opposite sign, i.e., inductive and capacitive. Their inherent propagation confinement, low-losses and robustness towards imperfections are attractive characteristics that have recently pushed the efforts of the community in the field. Still, a straightforward procedure for designing guiding structures supporting this edge mode is not available. In this contribution, we describe a simple workflow for designing waveguides supporting 1D modes propagation. The workflow involves a proper combination of analytical tools and full-wave numerical simulations and allows quickly retrieving the final geometries of the complementary metasurfaces composing the waveguides. In addition, we discuss several layouts supporting line-wave propagation and compare their transmission performance. The results of the experimental measurements carried out on some manufactured prototypes are also reported to assess the effectiveness of the design approach and the suitability of line-wave waveguides for low-loss wave propagation

Role of orexin-1 receptor mechanisms on compulsive food consumption in a model of binge eating in female rats

Orexins (OX) and their receptors (OXR) modulate feeding, arousal, stress, and drug abuse. Neural systems that motivate and reinforce drug abuse may also underlie compulsive food seeking and intake. Therefore, the effects of GSK1059865 (5-bromo-N-[(2S,5S)-1-(3-fluoro-2-methoxybenzoyl)-5-methylpiperidin-2-yl]methyl-pyridin-2-amine), a selective OX1R antagonist, JNJ-10397049 (N-(2,4-dibromophenyl)-N′-[(4S,5S)-2,2-dimethyl-4-phenyl-1,3-dioxan-5-yl]urea), a selective OX2R antagonist, and SB-649868 (N-[((2S)-1-{[5-(4-fluorophenyl)-2-methyl-1,3-thiazol-4-yl]carbonyl}-2-piperidinyl)methyl]-1-benzofuran-4-carboxamide), a dual OX1/OX2R antagonist were evaluated in a binge eating (BE) model in female rats. BE of highly palatable food (HPF) was evoked by three cycles of food restriction followed by stress, elicited by exposing rats to HPF, but preventing them from having access to it for 15 min. Pharmacokinetic assessments of all compounds were obtained under the same experimental conditions used for the behavioral experiments. Topiramate was used as the reference compound as it selectively blocks BE in rats and humans. Dose-related thresholds for sleep-inducing effects of the OXR antagonists were measured using polysomnography in parallel experiments. SB-649868 and GSK1059865, but not JNJ-10397049, selectively reduced BE for HPF without affecting standard food pellet intake, at doses that did not induce sleep. These results indicate, for the first time, a major role of OX1R mechanisms in BE, suggesting that selective antagonism at OX1R could represent a novel pharmacological treatment for BE and possibly other eating disorders with a compulsive component