A review on improved design techniques for high performance planar waveguide slot arrays

Planar waveguide slot arrays (WSAs) have been used since 1940 and are currently used as performing antennas for high frequencies, especially in applications such as communication and RADAR systems. We present in this work a review of the most typical waveguide slot array configurations proposed in the literature, describing their main limitations and drawbacks along with possible effective countermeasures. Our attention has been focused mainly on the improved available design techniques to obtain high performance WSAs. In particular, the addressed topics have been reported in the following. Partially filled WSAs, or WSAs covered with single or multilayer dielectric slabs, are discussed. The most prominent second-order effects in the planar array feeding network are introduced and accurately modeled. The attention is focused on the T-junction feeding the array, on the effect of interaction between each slot coupler of the feeding network and the radiating slots nearest to this coupler, and on the waveguide bends. All these effects can critically increase the first sidelobes if compared to the ideal case, causing a sensible worsening in the performance of the arra

A Multidisciplinary Approach to the Study of Early Neolithic Pyrotechnological Structures. The Case Study of Portonovo (Marche, Italy)

The introduction of agricultural practices fostered the development of specific technologies for the new subsistence practices and the production of new artefacts. Pyrotechnological structures such as ovens are part of the Neolithic equipment and accompanied the spread of agriculture from the Near East across Europe and the Mediterranean Sea. Ovens located within settlements – mainly domed, aboveground structures – have been traditionally linked to cooking and baking. The function is usually deduced from techno-morphological traits, although experimental approaches or ethnoarchaeological observations have often been used. This article aims to demonstrate the effectiveness of the multidisciplinary approach to understand the function of fire structures. An integrated methodology that combines archaeological analysis, archaeometry, and experimental archaeology has been applied to study the underground ovens of the Early Neolithic site of Portonovo (Marche, Italy) dated to the sixth millennium BCE. Samples of hardened sediment of archaeological ovens’ inner surface and selected pottery fragments were analysed through X-ray powder diffraction to estimate the temperature reached. A life-size replica of an underground oven was then created to perform firing experiments, including pottery firing. Samples of the oven’s walls and experimental vessels were analysed with the same method, and the values were compared. Our results indicate that the Portonovo ovens are potentially multifunctional structures, built for about 700 years, always with the same technique exploiting the natural soil’s insulating properties

SiLiBA: Building the geological chert lithotheque

Lithotheques collect and exhibit raw material used by human communities for the manufacturing of objects during the Prehistory and represents an important tool of their knowledge. These collections are essential in the procuring and provenance study of archaeological lithic industries. This paper aims, firstly, to introduce SiLiBA, the lithotheque of the Earth and Geoenvironmental Sciences Department of the University of Bari Aldo Moro (Italy), as reference collection in the archaeological field studies, and secondly to propose guidelines and rules to build a lithotheque. The collection consists of about 900 pieces of geological cherts, which are the result of an expanded collecting action of primary and secondary cherts across Italy (Apulia, Basilicata, Sicily), Croatia, and Switzerland, belonging to formations from the Cretaceous to the Quaternary Period. All the chert samples were described according to the non-destructive multiparametric protocol for chert investigation (NM-PCI), providing a modular dataset of binary, ordinal and continuous variables which integrates petrographycal, micropaleontological, chemical and physical data. Such results were summarized in suitable reports, with also geographic coordinates, geological description and photographic documentation, in a digital database, which will be soon online. Cherts are grouped in 37 suitable boxes, following geographic hierarchical organisation and reporting informative labels. Some representative samples are exposed in the Earth Sciences Museum of the same University. Furthermore, the lithotheque is equipped by a dedicated laboratory which includes optical microscopes, a glossmeter and a spectrophotocolorimeter. The promotion in the last years was guaranteed by dissemination activities for educational and academic communities, including an interactive laboratory of experimental archaeology

A Coaxial Line Fixture Based on a Hybrid PSO-NLR Model for in Situ Dielectric Permittivity Determination of Carasau Bread Dough

Food quality is crucial in today's processing industry. The organoleptic properties of most food materials are known to depend on their water content. The monitoring of food quality and moisture content calls for engineering solutions. To this aim, given their nondestructive nature and cost-effective features, microwave sensors are a valuable tool. However, for some peculiar food processing industries, suitable engineered microwave devices must be designed. Therein, we will focus on the case of the Carasau bread industry. Carasau bread is a typical food product from Sardinia (IT). In this work, we will present the design, realization, and characterization of a coaxial fixture, working between 0.5 and 3 GHz, for the determination of the complex dielectric permittivity of Carasau bread dough. Through a nonlinear regression model based on a particle swarm optimization routine, the scattering parameters are used to retrieve the electromagnetic properties of bread doughs. By making a comparison with the complex dielectric permittivity measured with an open-ended coaxial probe, an average error of 3% for the real part and 6% for the imaginary part has been found. The proposed device is driven by a Raspberry Pi that controls the acquisition of a pocket-vector network analyzer (VNA), thus representing a cost-effective electronic system for industrial applications

Metabolomics and psychological features in fibromyalgia and electromagnetic sensitivity

Fibromyalgia (FM) as Fibromyalgia and Electromagnetic Sensitivity (IEI-EMF) are a chronic and systemic syndrome. The main symptom is represented by strong and widespread pain in the musculoskeletal system. The exact causes that lead to the development of FM and IEI-EMF are still unknown. Interestingly, the proximity to electrical and electromagnetic devices seems to trigger and/or amplify the symptoms. We investigated the blood plasma metabolome in IEI-EMF and healthy subjects using 1H NMR spectroscopy coupled with multivariate statistical analysis. All the individuals were subjected to tests for the evaluation of psychological and physical features. No significant differences between IEI-EMF and controls relative to personality aspects, Locus of Control, and anxiety were found. Multivariate statistical analysis on the metabolites identified by NMR analysis allowed the identification of a distinct metabolic profile between IEI-EMF and healthy subjects. IEI-EMF were characterized by higher levels of glycine and pyroglutamate, and lower levels of 2-hydroxyisocaproate, choline, glutamine, and isoleucine compared to healthy subjects. These metabolites are involved in several metabolic pathways mainly related to oxidative stress defense, pain mechanisms, and muscle metabolism. The results here obtained highlight possible physiopathological mechanisms in IEI-EMF patients to be better defined

Crowded space: A review on radar measurements for space debris monitoring and tracking

Space debris monitoring is nowadays a priority for worldwide space agencies, due to the serious threat that these objects present. More and more efforts have been made to extend the network of available radar systems devoted to the control of space. A meticulous review has been done in this paper, in order to find and classify the considerable amounts of data provided by the scientific community that deal with RADAR measurement for the debris monitoring and tracking. The information gathered is organized based on the volume of found data and classified taking into account the geographical location of the facilities

Design of a Low-Profile Dual Linearly Polarized Antenna Array for mm-Wave 5G

This work proposes a dual linearly polarized antenna array for 5G mm-wave band, which is designed to be compatible with planar printed circuit board technology. The proposed antenna is engineered with a focus on simplifying the antenna geometry and eliminating any critical issues that may arise in antenna manufacturing. The proposed antenna has been evaluated, finding a 7% impedance bandwidth centered around 27.28 GHz. Additionally, the beam steering capability of the antenna is found to cover a ±30% angular width for both linear polarizations. These findings highlight the potential of the proposed antenna for use in 5G mm-wave band applications, where compatibility with planar printed circuit board technology and simplified antenna geometry are essential design requirements

A Low-profile Shared Aperture Antenna for FR1 and FR2 5G Frequency Bands

Shared-aperture antennas are attracting a wide interest in last of years, due to their inherent compactness and low-profile layout. More specifically, in this work a shared-aperture antenna for FR1 and FR2 frequency bands is proposed. The difference in size between the radiating elements operating the two frequency bands can be exploited to embed different antennas in the same area. A 4×4 patch array for FR2 is embedded inside a FR1 shaped patch antenna. The antenna system is designed by preserving a low-profile architecture suitable for planar technology. The performance of the antenna system are evaluated for both the bands achieving a 10-dB bandwidth equal to 0.14 GHz (3.8 %) for FR1 and to 2.32 GHz (8.6 %) for FR2. In FR2, a ±30° steering capability along the H plane is shown

Space Debris Detection in Low Earth Orbit with the Sardina Radio Telescope

Space debris are orbiting objects that represent a major threat for space operations. In this work a bistatic radar configuration named BIstatic RAdar for LEo Tracking (BIRALET) is used to detect a set of space debris. Signalto- Noise Ratios, Doppler shift measures as well as the frequency specters for each debris are presented

Upgrading the Sardinia Radio Telescope to a bistatic tracking radar for space debris

In order to prevent the harmful impacts for spacecrafts deriving from the presence of space debris, many surveillance and monitoring programs of the space environment have been started in recent years. The Sardinia Radio Telescope is a new comer in such a scenario, but it has already showed its potential. However, since the actual receiving chain is not optimized for the reception of the echoes scattered from the debris, some modifications has been planned to upgrade the telescope and made it suitable for these types of observations