TTI (Spain)

This article presents the design and experimental characterization of an engineering model (EM) solid-state power amplifier (SSPA) based on European 0.5-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula>m gallium nitride (GaN) on silicon carbide technology, conceived for next-generation flexible L-band navigation payloads. Operating in the E1 band (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1575.42\pm 25$</tex-math> </inline-formula> MHz), the unit integrates a radio frequency tray (RFT) to amplify the useful signal, and an electronic power conditioner (EPC), which provides telecommand/telemetry functions, remote mode selection, and interfaces the module with the satellite primary bus. Continuous-wave measurements demonstrate an adjustable output power range from 50.8 to 54.8 dBm with efficiency above 41%, including EPC consumption and connector/isolator losses. The amplifier also exhibits excellent thermal stability, with output power variation below 0.1 dB across −20 °C to +65 °C temperature range. Under Galileo-like modulated signals, it ensures full compliance with the spectral emission masks, thanks to an embedded analog linearizer (LIN), while delivering up to 300-W average output power with efficiencies up to 48%. The SSPA is multipaction free and fulfills all the space derating rules in terms of junction temperature and voltage/current swings for the involved GaN active devices. Compared with previously reported GaN SSPAs, the proposed design uniquely combines embedded output power flexibility and analog linearization in a compact, lightweight, space-ready unit. In particular, its power flexibility enables a reduction of more than 130 W in dc power consumption in low-power mode, easing thermal management and enhancing reliability, thus offering a valid solution for implementing high-reliability next-generation reconfigurable satellite payloads entirely based on solid-state technology.

ABSTRACT Background/Purpose Flow diverter porosity directly influences the blood flow reduction at the aneurysm neck level and the anatomical result of the treatment. In this research, we present and compare three methodologies to determine the local porosity of deployed flow diverters. Method Three-dimensional rotational angiography was used to obtain computational vessel models of three patients. Different flow diverters were virtually deployed in the computational models and implanted in 3D-printed models of the vasculatures by interventional neuroradiologists. Experimental porosity determinations were conducted using 2D microscope photographs and 3D Dyna-CT images (i.e. cone-beam Computed Tomography angiographic images), while simulated porosity was computed using ANKYRAS software. Results No statistically significant differences were observed between the porosity distributions from the three methods (p > 0.01). When computing the differences point-by-point, narrow distributions centered on zero were obtained, revealing a good agreement in the determinations. Orthogonal regression analysis affirmed this equivalence. The lowest agreement between porosity measurement methods was observed to occur at curve segments with relatively low porosity. Conclusions The local porosity of deployed flow diverters can be accurately determined by the three methods presented in this work. Assessing FD porosity with 3D Dyna-CT images would allow the evaluation of real patient data, whereas simulations could determine local porosity before the treatment.

This paper addresses the complete process of design, optimization, manufacturing and testing of a vector array of eight longitudinal slots, devised to work on the W band with a uniform amplitude taper distribution. Comparison between simulations and measurements are shown, revealing an almost perfect match in both radiation pattern and return losses.

In-flight communication (IFC) services offered to passengers and crew are of great importance to the air transport sector. The improvement of the satellite capacity with High Throughput Satellites (HTS) in GEO and the advent of MEO and LEO constellations will support the forecast growth of the IFC market. Antenna equipment for satellite communications will need to address multiple scenarios from G2G (Gate-to-Gate) to multi-operation under GEO-MEO-LEO systems. Under these conditions, antennas with the ability to track multiple satellites and having superior performance and reliability will play a key role. Electronically steered antennas (ESA) have emerged as a viable solution in response to these demands. The EU-funded LESAF project proposes an ESA solution of reduced size and greater efficiency for the next generation of in-flight connectivity services. This will be managed through the requirements definition, system analysis, technology assessment, prototyping and validation of ESAs. The project has successfully passed the first milestone corresponding to requirements consolidation, baseline architecture definition and candidate technology trade-offs. Multi-beam Electronically Steered Antennas, separated apertures for both transmission and reception, a flexible modular approach coupled with planar multilayer integration and an advanced beamformer design are the basis for the proposed concept. The following project phase will be focused on the design and validation of an antenna demonstrator aimed at proving the superior added value of ESAs technological solution for the aviation industry needs.

A person's death is deemed unnatural when it is the result of an external force. This definition, however, does not apply when the cause of death is a respiratory or cardiovascular process triggered by a high concentration of an air pollutant, even if other deaths from toxicological causes (poisonings, overdoses, etc.) are. The distinction between natural and unnatural cause of death, although not internationally standardized, is critical in determining wrongfulness and liability, which in turn can have financial and/or legal repercussions. Even though the World Health Organization and other medical and scientific organizations have shown that air pollution contributes to several million deaths every year, there are currently no practical means to determine whether a person was subjected to high concentrations of atmospheric pollution before their death; indeed, the ability to find evidence of this type of exposition could prove very interesting from a forensic standpoint.

Processing data that originates from different sources (such as environmental and medical data) can prove to be a difficult task, due to the heterogeneity of variables, storage systems, and file formats that can be used. Moreover, once the amount of data reaches a certain threshold, conventional mining methods (based on spreadsheets or statistical software) become cumbersome or even impossible to apply. Data Extract, Transform, and Load (ETL) solutions provide a framework to normalize and integrate heterogeneous data into a local data store. Additionally, the application of Online Analytical Processing (OLAP), a set of Business Intelligence (BI) methodologies and practices for multidimensional data analysis, can be an invaluable tool for its examination and mining. In this article, we describe a solution based on an ETL + OLAP tandem used for the on-the-fly analysis of tens of millions of individual medical, meteorological, and air quality observations from 16 provinces in Spain provided by 20 different national and regional entities in a diverse array for file types and formats, with the intention of evaluating the effect of several environmental variables on human health in future studies. Our work shows how a sizable amount of data, spread across a wide range of file formats and structures, and originating from a number of different sources belonging to various business domains, can be integrated in a single system that researchers can use for global data analysis and mining.

In this paper, authors present the preliminary measurements of a PWM-based transmitter. It is realised by cascading a pulse width modulator and a driver stage (PWCD), with a high efficiency Class E switched mode power amplifier (SMPA). The PWCD was realized by using 250nm BiCMOS process from IHP (SGB25V GD), while the SMPA was realized by using a packaged GaN device from UMS (CHK040A-SOA). The preliminary results showed output power levels higher than 40W with efficiency close to 70 %.

An L-Band high power and efficient solid state power amplifier (SSPA) designed for the European satellite navigation system (i.e., Galileo) is presented. The developed SSPA, based on European Gallium Nitride (GaN) technology, comprises all the circuits required to interface the module with the satellite bus (i.e., a Power Supply Unit, PSU), and to control its functionalities by remote telecomand and telemetry (i.e., an Electronic Power Conditioner unit, EPC). The Radio frequency Unit (RFU) together with the PSU and EPC are accommodated in a single box with limited volume and mass. In continuous wave operating mode, the SSPA delivers an output power higher than 300W at less than 3 dB of gain compression in the whole E1-Band (i.e., center frequency ƒ0 = 1.575GHz). Moreover, the demonstrated gain and power added efficiency, including the power dissipated by the PSU and EPC, are higher than 65 dB and 44 %, respectively.

This paper describes the development of an L-Band (f0= 1.575 GHz) high power and efficient solid state power amplifier (SSPA) designed for the European satellite navigation system (i.e. Galileo). The amplifier, developed in the framework of the European Project named SLOGAN, exploits the GH50-10 GaN technology available at United Monolithic Semiconductor foundry. The aim of the project is to offer, using as much as possible European technologies, a valid alternative to replace traveling wave tube amplifiers with more compact and reliable systems. All the SSPA functionalities, i.e. power supply, power conditioning and radio frequency amplification, are integrated in the developed architecture and accommodated in a single box with limited volume and mass. The required output power level is achieved by parallelizing several GaN die power bars of 12 and/or 25.6 mm. In continuous wave operating mode, the overall SSPA delivers an output power higher than 250 W at less than 2 dB of gain compression in the whole E1-band. Moreover, the registered gain and efficiency are higher than 67 dB and 54%, respectively.