Simple analytical models for the calculation of the electric field radiated by the base station antenna

This paper outlines four different models for the assessment of the electric field radiated by the base station antenna system, thus featuring the Free Space Model (FS), Perfect Ground Model (PG), Fresnel Reflection Coefficient Model (RC) and Modified Image Theory Model (MIT). The results obtained with these approaches are compared to the results computed via Numerical Electromagnetics Code (NEC). Several variables have been varied to examine the accuracy of each calculation model. The calculations have been undertaken for the far field only. As many European countries perform the field assessment using the FS model, the final goal of this work is to come up with the most convenient model for the field calculation

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Engineering Feasibility Study of a Kilometer Wave Orbiting Telescope, Phase 1 Final Report

Radio telescope, rhombic antenna, and sensors studied for feasibility of kilometer wave orbit telescope progra

Antennas and Propagation for UAV-Assisted Wireless Networks Towards Next Generation Mobile Systems

Unmanned Aerial Vehicles (UAV), also known as "drones", are attracting increasing attention as enablers for many technical applications and services, and this trend is likely to continue in the near future. UAVs are expected to be used extensively in civil and military applications where aerial surveillance and assistance in emergency situations are key factors. UAVs can be more useful and flexible in reaction to specific events, like natural disasters and terrorist attacks since they are faster to deploy, easier to reconfigure and assumed to have better communication means due to their improved position in the sky, improved visibility over ground, and reduced hindrance for propagation. In this regard, UAV enabled communications emerge as one of the most promising solutions for setting-up the next-generation mobile networks, with a special focus on the extension of coverage and capacity of mobile radio networks for 5G applications and beyond. However, air-to-ground (A2G) propagation conditions are likely to be different and more challenging than those experienced by traditional piloted aircraft. For this reason, knowledge of this specific propagation channel – together with the UAV antenna design and placement - is paramount for defining an efficient communication system and for evaluating its performance. This PhD thesis tackles this challenge, and it aims at further investigating the narrowband properties of the air-to-ground propagation channel by means of GPU accelerated ray launching simulations for 5G communications and beyond. As a conclusion, this PhD thesis might bring deep insights into the air-to-ground channel characteristics and UAV antenna design, which can be helpful for designing UAV communication networks and evaluating or optimising their performances in a fast and reliable manner, with no need for exhausting – multiple - in-field measurement campaigns

Radio Echo Sounding Studies of Svalbard Glaciers

The objective of this study was to investigate the radio echo sounding properties of Svalbard glaciers and to use these data to obtain information about the glaciological environment. Particular emphasis was placed on obtaining an understanding of the dielectric properties of the ice and reflecting boundaries present. These were then used to elucidate the physical processes causing them. First, a theoretical model, describing the dielectric properties of a wet bed, was developed. The ice/bed interface was then investigated using, as the primary data source, radar reflection coefficients. From these data inferences about the presence of water and/or debris, roughness of the interface and geographical trends were made. A number of geological divides were detected. Second, the dielectric properties of Svalbard ice were considered using i) radio echo sounding data on the bulk in situ radar absorption and ii) measurements made on the dielectric properties of a sample of Spitsbergen ice. Data were collected between 20 Hz and 100 kHz in the temperature range -2.5 to -44.0C . From these and other data deductions about the thermal regime of the ice masses were made and a geographical trend, linked to the reflection coefficients, observed. The theory of dielectric absorption in ice was discussed with an emphasis on the high frequency, radio echo sounding characteristics. Third, the properties of an extraordinary internal reflecting horizon ( observed on 60% of the glaciers sounded in 1983) were investigated. A model was developed to describe the scattering properties of inhomogeneities ( of arbitrary size) within ice. Using this, and data on the re:flec~ing properties of the horizons, they were attributed to the presence of a finite quantity of water. The implications of this finding were considered. Finally, the surface and, where available, bedrock profiles of 40 glaciers and six ice caps, in Spitsbergen, were presente