1,721,021 research outputs found
A Mortar-Element Method for the Analysis of Cylindrical Guiding Structures
No full textIn this work a novel formulation for the analysis of structures with axial symmetry is presented. A multi-domain spectral method based on mortar-matching is developed. The technique is applied to the analysis and design of smooth-wall horn antennas. A comparison of the simulation results obtained with this numerical scheme and with a mode-matching code is presented
Array Elements for LEO SatCom Payloads
Full text linkWith each generation of mobile communications, there is an exponential demand for both data transmission and a larger coverage footprint. One of the proposed solutions to these needs may be the deployment of communications via low orbit satellites, LEO SatCom. For this purpose, different types of antennas have been reviewed, such as waveguide-based aperture and All-Metal Vivaldi antenna
3D-Printing of Antenna-Feed Components for Space Applications
No full textThis paper reports an overview on the on-going research activity aimed at the exploitation of 3D-printing technologies to the development of dual-band and dual-polarization components for SatCom antenna feed chains. In particular, architectures optimized for 3D-printing are discussed, and the results of a preliminary study on the application of perforations along the internal channels is reported
Platelet Orthomode Transducer for Q -Band Correlation Polarimeter Clusters
No full textThis paper presents a Q-band orthomode transducer (OMT) that has been designed according to the mechanical constraints of the platelet (multi-layer) manufacturing strategy. It is composed of a twofold symmetric coupling section with two electrically identical recombination networks. The two OMT outputs lay on the same plane to provide a suitable interface to the correlation unit. The two channels are equalized in both magnitude and phase according to the correlation polarimeter requirements. They also exhibit a very low cross-coupling (-50 dB) and good reflection levels (-28 dB) in the 21% bandwidth
Electromagnetics-Aware Path for UAV-Based Near-Field Antenna Measurements Implemented With a High Dynamic Range SDR
Full text linkAn electromagnetics-aware path for drone-based near-field (NF) antenna measurements is implemented in an outdoor experimentation. This technique allows us to significantly reduce the scan duration with respect to a standard half-wavelength NF scanning, using knowledge of the antenna under test (AUT) electrical size only. The validity of our approach is corroborated with planar outdoor NF measurements performed with an untethered drone transmitting at 750 MHz. To deal with the absence of phase coherence, the phase information is retrieved from a reference antenna, while a software-defined radio (SDR) having four super-heterodyne receiving channels is used to properly sample the high-dynamic signals resulting from the large scanning surface
Multi-Beam Arrays for Future LEO SatCom Payloads
Full text linkLEO satellite antennas must provide several beams at the same time up to Ka-band over a large scanning angle (up to ±60°). For this reason, high performance radiating elements and beamforming circuitry becomes crucial for the development of new constellations. This paper outlines the challenges and limitations of both waveguide-based and Vivaldi-based solutions and their impact on the beam-formed patterns
W-Band Orthomode Transducer for Dense Focal-Plane Clusters
No full textA W-band orthomode transducer has been designed for polarimeter clusters in dense focal planes. Its compact geometry, with aligned output ports, allows for a closely-spaced triangular-lattice arrangement. At these high frequencies, the platelet manufacturing strategy has been applied and verified experimentally on seven prototypes, showing reflection coefficients lower than polarimeter clusters-20 dB, insertion loss of about 0.25 dB and cross-coupling and isolation levels of -42 dB and 45 dB, respectively, in a 30% bandwidt
Analysis and design of passive waveguide devices by spectral element methods
No full textThis work will present a spectral-element method suitable for the efficient design
of two-dimensional passive waveguide components. The method exploits
different domain mappings in order to correctly model the singular behavior of
the field close to sharp edges also in presence of curved sides. Several devices
for satellite communication and scientific instrumentation have successfully
been designed with the present technique. Detailed comparison between
simulated and measured performances will prove the reliability of the method
also when very demanding specifications are set on components desig
Effect of thermal treatments on the surface electrical conductivity of AlSi7Mg produced by laser powder bed fusion
Full text linkIn the last years, the production of hypoeutectic Al-Si waveguide components by metal additive manufacturing
has gained increasing attention in the telecommunications industry. The performances of waveguide components
are influenced primarily by dimensional tolerances, surface electrical conductivity, surface roughness, and
dimensional accuracy. Among these properties, electrical conductivity is known to be strongly influenced by the
structural and microstructural characteristics of the alloys.
In this work, microstructural and structural properties of an hypoeutectic Al-Si alloy, namely the AlSi7Mg
alloy, were studied using FESEM, DSC, and XRD to understand how different thermal treatments (stress relieving,
T5, and T6) affect the surface electrical conductivity. In the end, the most suitable thermal treatment to be
applied to this alloy to maximize its electrical conductivity and, therefore, its appeal for microwave waveguide
components is identified
UAV-based antenna verification system: extracted AUT pattern
No full textA novel far-field antenna pattern verification system based on a flying test source has been recently published [1]. It directly performs the antenna validation considering the received power level at the antenna port. This paper
discusses an extraction procedure to obtain the antenna pattern from such measured data. Significant results obtained on a log-periodic antenna operating at 408 MHz are also reported
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