292 research outputs found
Introduction to Drone Detection Radar with Emphasis on Automatic Target Recognition (ATR) technology
This paper discusses the challenges of detecting and categorizing small
drones with radar automatic target recognition (ATR) technology. The authors
suggest integrating ATR capabilities into drone detection radar systems to
improve performance and manage emerging threats. The study focuses primarily on
drones in Group 1 and 2. The paper highlights the need to consider kinetic
features and signal signatures, such as micro-Doppler, in ATR techniques to
efficiently recognize small drones. The authors also present a comprehensive
drone detection radar system design that balances detection and tracking
requirements, incorporating parameter adjustment based on scattering region
theory. They offer an example of a performance improvement achieved using
feedback and situational awareness mechanisms with the integrated ATR
capabilities. Furthermore, the paper examines challenges related to one-way
attack drones and explores the potential of cognitive radar as a solution. The
integration of ATR capabilities transforms a 3D radar system into a 4D radar
system, resulting in improved drone detection performance. These advancements
are useful in military, civilian, and commercial applications, and ongoing
research and development efforts are essential to keep radar systems effective
and ready to detect, track, and respond to emerging threats.Comment: 17 pages, 14 figures, submitted to a journal and being under revie
Doctor of Philosophy
dissertationTARA (Telescope Array Radar) is a cosmic ray radar detection experiment co- located with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, UT. The TARA detector combines a 40 kW transmitter and high gain transmitting antenna which broadcasts the radar carrier over the SD array and in the FD field of view to a 250 MS/s DAQ receiver. Data collection began in August, 2013. TARA stands apart from other cosmic ray radar experiments in that radar data is directly compared with conventional cosmic ray detector events. The transmitter is also directly controlled by TARA researchers. Waveforms from the FD-triggered data stream are time-matched with TA events and searched for signal using a novel signal search technique in which the expected (simulated) radar echo of a particular air shower is used as a matched filter template and compared to radio waveforms. This technique is used to calculate the radar cross-section (RCS) upper-limit on all triggers that correspond to well-reconstructed TA FD monocular events. Our lowest cosmic ray RCS upper-limit is 42 cm^2 for an 11 EeV event. An introduction to cosmic rays is presented with the evolution of detection and the necessity of new detection techniques, of which radar detection is a candidate. The software simulation of radar scattering from cosmic rays follows. The TARA detector, including transmitter and receiver systems, are discussed in detail. Our search algorithm and methodology for calculating RCS is presented for the purpose of being repeatable. Search results are explained in context of the usefulness and future of cosmic ray radar detection
Antennas and Propagation
This Special Issue gathers topics of utmost interest in the field of antennas and propagation, such as: new directions and challenges in antenna design and propagation; innovative antenna technologies for space applications; metamaterial, metasurface and other periodic structures; antennas for 5G; electromagnetic field measurements and remote sensing applications
Three-Dimensional Electromagnetic Scattering from Layered Media with Rough Interfaces for Subsurface Radar Remote Sensing
The objective of this dissertation is to develop forward scattering models for active microwave remote sensing of natural features represented by layered media with rough interfaces. In particular, soil profiles are considered, for which a model of electromagnetic scattering from multilayer rough surfaces with/without buried random media is constructed.
Starting from a single rough surface, radar scattering is modeled using the stabilized extended boundary condition method (SEBCM). This method solves the long-standing instability issue of the classical EBCM, and gives three-dimensional full wave solutions over large ranges of surface roughnesses with higher computational e±ciency than pure numerical solutions, e.g., method of moments (MoM). Based on this single surface solution, multilayer rough surface scattering is modeled using the scattering matrix approach and the model is used for a comprehensive sensitivity analysis of the total ground scattering as a function of layer separation, subsurface statistics, and sublayer dielectric properties.
The buried inhomogeneities such as rocks and vegetation roots are considered for the first time in the forward scattering model. Radar scattering from buried random media is modeled by the aggregate transition matrix using either the recursive transition matrix approach for spherical or short-length cylindrical scatterers, or the generalized iterative extended boundary condition method we developed for long cylinders or root-like cylindrical clusters. These approaches take the field interactions among scatterers into account with high computational efficiency. The aggregate transition matrix is transformed to a scattering matrix for the full solution to the layered-medium problem. This step is based on the near-to-far field transformation of the numerical plane wave expansion of the spherical harmonics and the multipole expansion of plane waves. This transformation consolidates volume scattering from the buried random medium with the scattering from layered structure in general. Combined with scattering from multilayer rough surfaces, scattering contributions from subsurfaces and vegetation roots can be then simulated. Solutions of both the rough surface scattering and random media scattering are validated numerically, experimentally, or both. The experimental validations have been carried out using a laboratory-based transmit-receive system for scattering from random media and a new bistatic tower-mounted radar system for field-based surface scattering measurements.Ph.D.Electrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91459/1/xduan_1.pd
Radar observations of space debris in polar orbits 2018–2021. A study on the evolution of the Microsat-R fragments
Orbits are an invaluable resource for the global community. However, space
pollution is becoming more pronounced as the accumulation of debris continues.
Deliberate collisions are a relevant source contributing to this development.
When Microsat-R was destroyed with a missile in 2019, it ejected numerous
fragments into orbit. Based on observations made with EISCAT UHF, this thesis
will investigate the evolution of this debris cloud. This is achieved using the
results from four different measurement campaigns from 2018 to 2021
Suitability of a commercial software defined radio system for passive coherent location
Includes abstract.
Includes bibliographical references (leaves 98-99)
Experimental low-THz imaging radar for automotive applications
This thesis reports initial experimental results that provide the foundation for low-THz radar imagery for outdoor scenarios as expected in automotive sensing. The requirements for a low-THz single imaging radar sensor are outlined. The imaging capability of frequency-modulated continuous-wave (FMCW) radar operating at 150 GHz is discussed. A comparison of experimental images of on-road and off- road scenarios made by a 150 GHz FMCW radar and a reference 30 GHz stepped frequency radar is made, and their performance is analysed
Development of the epoxy composite complex permittivity and its application in wind turbine blades
PhDOffshore wind farm structures may have the potential to affect marine navigation and
communication systems by reflecting radar signals. With ever increasing size of wind
turbines it is necessary to better understand the influence of radar signals on wind
turbine blades in order to minimise the radar reflecting potential. One possible way of
reducing radar reflection is to use radar absorbing materials. In this thesis, epoxy
composite materials reinforced with five different types of nano-size additives: carbon
nanotubes (CNTs), carbon blacks (CBs), silver, tungsten carbide and titanium oxide
are manufactured and tested to investigated their potential as wind turbine blade
material that absorb radar signals.
Nanoadditives/epoxy composites with additives content ranging from 0.05-1 wt. %
were fabricated by a simple cast moulding process. The nanoadditives were dispersed
in the epoxy resin by sonication method. The degree of nanoadditives dispersion was
observed by examining the surface of the composite materials using scanning electron
microscope (SEM). Complex permittivity of the nanoadditives/epoxy composites was
studied using a free wave transmittance only method at a frequency range of 6.5-10.5
GHz. The effect of the percolation threshold of the direct current conductivity on the
composite permittivity was analysed and discussion. In order to get a better insight in
the importance of the results they were compared to existing models (Maxwell-
Garnett, Bruggeman, Bottcher, Lichtenecker and Lichtenecker-Rother). A new model
based rule of mixtures is developed to predict the complex permittivity of the
composite.
A model of wind turbine rotor blade made of the nanoadditives/epoxy composite was
developed using Comsol-multiphysics software. The data obtained from the
experimental work was inputted in to the model to generate result of backscattered
energy verses composite permittivity as a function of nanoadditives content. A
decrease in backscattered energy was noticed with increasing nanoadditives content.
The results demonstrate that radar reflecting signals will be significantly reduced by
incorporating nanoadditives in the composite materials
Experimental low-THz imaging radar for automotive applications
This thesis reports initial experimental results that provide the foundation for low-THz radar imagery for outdoor scenarios as expected in automotive sensing. The requirements for a low-THz single imaging radar sensor are outlined. The imaging capability of frequency-modulated continuous-wave (FMCW) radar operating at 150 GHz is discussed. A comparison of experimental images of on-road and off- road scenarios made by a 150 GHz FMCW radar and a reference 30 GHz stepped frequency radar is made, and their performance is analysed
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