85 research outputs found
Radar Technology
In this book “Radar Technology”, the chapters are divided into four main topic areas: Topic area 1: “Radar Systems” consists of chapters which treat whole radar systems, environment and target functional chain. Topic area 2: “Radar Applications” shows various applications of radar systems, including meteorological radars, ground penetrating radars and glaciology. Topic area 3: “Radar Functional Chain and Signal Processing” describes several aspects of the radar signal processing. From parameter extraction, target detection over tracking and classification technologies. Topic area 4: “Radar Subsystems and Components” consists of design technology of radar subsystem components like antenna design or waveform design
Remote Sensing
This dual conception of remote sensing brought us to the idea of preparing two different books; in addition to the first book which displays recent advances in remote sensing applications, this book is devoted to new techniques for data processing, sensors and platforms. We do not intend this book to cover all aspects of remote sensing techniques and platforms, since it would be an impossible task for a single volume. Instead, we have collected a number of high-quality, original and representative contributions in those areas
1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface
A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance
Microwave NDT&E using open-ended waveguide probe for multilayered structures
Ph. D. Thesis.Microwave NDT&E has been proved to be suitable for inspecting of dielectric structures due
to low attenuation in dielectric materials and free-space. However, the microwave responses
from multilayered structures are complex as an interrogation of scattering electromagnetic
waves among the layers and defects. In many practical applications, electromagnetic analysis
based on analytic- and forward structural models cannot be generalised since the defect shape
and properties are usually unknown and hidden beneath the surface layer.
This research proposes the design and implementation of microwave NDT&E system for
inspection of multilayered structures. Standard microwave open-ended rectangular waveguides
in X, Ku and K bands (frequency range between 8-26.5 GHz) and vector network analyser
(VNA) generating sweep frequency of wideband monochromatic waves have been used to
obtain reflection coefficient responses over three types of challenging multilayered samples: (1)
corrosion progression under coating, (2) woven carbon fibre reinforced polymer (CFRP) with
impact damages, and (3) thermal coated glass fibre reinforced polymer (GFRP) pipe with inner
flat-bottom holes. The obtained data are analysed by the selected feature extraction method
extracting informative features and verify with the sample parameters (defect parameters). In
addition, visualisation methods are utilised to improve the presentation of the defects and
material structures resulting in a better interpretation for quantitative evaluation.
The contributions of this project are summarised as follows: (1) implementation of microwave
NDT&E scanning system using open-ended waveguide with the highest resolution of 0.1mm x
0.1 mm, based on the NDT applications for the three aforementioned samples; (2) corrosion
stages of steel corrosion under coating have been successfully characterised by the principal
component analysis (PCA) method; (3) A frequency selective based PCA feature has been used
to visualise the impact damage at different impact energies with elimination of woven texture
influences; (4) PCA and SAR (synthetic aperture radar) tomography together with time-offlight extraction, have been used for detection and quantitative evaluation of flat-bottom hole
defects (i.e., location, size and depth).
The results conclude that the proposed microwave NDT&E system can be used for detection
and evaluation of multilayered structures, which its major contributions are follows.
(1) The early stages (0-12month) of steel corrosion undercoating has been successfully
characterised by mean of spectral responses from microwave opened rectangular
waveguide probe and PCA.
(2) The detection of low energy impact damages on CFRP as low as 4 Joules has been
archived with microwave opened rectangular waveguide probe raster scan together with
SAR imaging and PCA for feature extraction methods.
(3) The inner flat-bottom holes beneath the thermal coated GFRP up to 11.5 mm depth has
been successfully quantitative evaluated by open-ended waveguide raster scan using
PCA and 3-D reconstruction based on SAR tomography techniques. The evaluation
includes location, sizing and depth.
Nevertheless, the major downside of feature quantities extracted from statistically based
methods such as PCA, is it intensely relies on the correlation of the input dataset, and thus
hardly link them with the physical parameters of the test sample, in particular, the complex
composite architectures. Therefore, there are still challenges of feature extraction and
quantitative evaluation to accurately determine the essential parameters from the samples. This
can be achieved by a future investigation of multiple features fusion and complementary
features.Ministry of Science and Technology of Royal Thai Government
and Office of Educational Affairs, the Royal Thai Embass
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
one6G white paper, 6G technology overview:Second Edition, November 2022
6G is supposed to address the demands for consumption of mobile networking services in 2030 and beyond. These are characterized by a variety of diverse, often conflicting requirements, from technical ones such as extremely high data rates, unprecedented scale of communicating devices, high coverage, low communicating latency, flexibility of extension, etc., to non-technical ones such as enabling sustainable growth of the society as a whole, e.g., through energy efficiency of deployed networks. On the one hand, 6G is expected to fulfil all these individual requirements, extending thus the limits set by the previous generations of mobile networks (e.g., ten times lower latencies, or hundred times higher data rates than in 5G). On the other hand, 6G should also enable use cases characterized by combinations of these requirements never seen before, e.g., both extremely high data rates and extremely low communication latency). In this white paper, we give an overview of the key enabling technologies that constitute the pillars for the evolution towards 6G. They include: terahertz frequencies (Section 1), 6G radio access (Section 2), next generation MIMO (Section 3), integrated sensing and communication (Section 4), distributed and federated artificial intelligence (Section 5), intelligent user plane (Section 6) and flexible programmable infrastructures (Section 7). For each enabling technology, we first give the background on how and why the technology is relevant to 6G, backed up by a number of relevant use cases. After that, we describe the technology in detail, outline the key problems and difficulties, and give a comprehensive overview of the state of the art in that technology. 6G is, however, not limited to these seven technologies. They merely present our current understanding of the technological environment in which 6G is being born. Future versions of this white paper may include other relevant technologies too, as well as discuss how these technologies can be glued together in a coherent system
13th Annual Review of Progress in Applied Computational Electromagnetics at the Naval Postgraduate School, Monterey, CA, March 17-21, 1997, Conference Proceedings Volumes I & II
Includes Volumes 1 &
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