Multi-band and dual-polarised ultra-wide band horn antenna for landmine detection using ground penetrating radar technique

Anti-Personnel (AP) and Anti-Vehicle (AV) landmines are considered as a problem of global proportions and it is estimated that about 60-70 million landmines are scattered within at least 70 countries all over the world. Many of the landmines are made with minimum metal content so that certain detection methods, such as metal detectors, often tend to fail. A promising concept for the detection of buried non-metallic objects is Ground Penetrating Radar (GPR). Although GPR has shown some promising results, the diversity and complexity of the problem inflict certain challenges on the operation of GPR systems. The investigations discussed in this thesis cover important aspects of GPR with particular focus on design of a new Ultra-Wideband (UWB) antenna. A systematic approach is adopted to show the GPR modelling process, and understanding the fundamental principles of GPR technology. The resolution of GPR highlights the importance of operating bandwidth. RF characterisation of materials is another aspect of GPR that will be addressed by the measurement of the relative permittivity of the materials. A novel multifunctional, multi-channel antenna design is proposed to enable the investigation of multiband imaging technique in GPR. The antenna is fabricated and the experimental measurements verify the performance of the designed antenna. The GPR results of 3D printed landmine models and real landmines in various environmental conditions have confirmed, the detection capability of the designed antenna. The GPR results of the landmines have also been investigated to study characteristic signatures of the landmines under certain system parameters

Remote Sensing of World War II Era Unexploded Bombs Using Object-Based Image Analysis and Multi-Temporal Datasets: A Case Study of the Fort Myers Bombing and Gunnery Range

During World War II, United States Army and Navy pilots trained on several hundred bombing ranges encompassing more than 12 million acres of land, leaving behind crater-scarred landscapes across the country. Post-war estimates suggest that 10-15% of aerial bombs used failed to detonate as intended, so these areas today are contaminated by a large number of dangerous unexploded bombs (UXB) which remain under the surface. Until recently, detecting UXB has been a tedious and expensive process done in three stages: (1) identifying and mapping general areas of concentrated bomb craters using historical air photos and records; (2) intensely searching these areas at a larger scale for much smaller UXB entry holes; and (3) confirming the presence of individual UXB using magnetometry or ground-penetrating radar. This research aims to streamline the workflow for stage 1 and 2 using semi-automated object-based image analysis (OBIA) methods with multi-source high spatial-resolution imagery. Using the Fort Myers Bombing and Gunnery Range in Florida as a study area, this thesis determines what OBIA software and Imagery is best at locating UXB in this environment. I assess the use of LiDAR-derived DEMs, historical air photos and high-resolution color digital orthophotos in Feature Analyst and Imagine Objective, and discuss optimal inputs and configurations for UXB searches in karst wetlands. This methodology might be applied by the detection and clearance industry in former war zones, and aid in restoring former training ranges to safe land uses in the U.S

Guidebook on Detection Technologies and Systems for Humanitarian Demining

The aim of this publication is to provide the mine action community, and those supporting mine action, with a consolidated review and status summary of detection technologies that could be applied to humanitarian demining operations. This Guidebook is meant to provide information to a wide variety of readers. For those not familiar with the spectrum of technologies being considered for the detection of landmines and for area reduction, there is a brief overview of the principle of operation for each technology as well as a summary listing of the strengths, limitations, and potential for use of the technology to humanitarian demining. For those with an intermediate level of understanding for detection technologies, there is information regarding some of the more technical details of the system to give an expanded overview of the principles involved and hardware development that has taken place. Where possible, technical specifications for the systems are provided. For those requiring more information for a particular system, relevant publications lists and contact information are also provided

Exploitation and Mitigation of Multipath in Complex Wave Propagation Environments for Target Detection, Tracking, and Communication.

This thesis introduces novel wave propagation models and RF based techniques for detection, tracking, and communication in highly cluttered environments. The applications of interest include localization of deeply submerged targets such as UXO and clandestine tunnels, real-time positioning and tracking of small robotic platforms for search and rescue missions, and enhanced situational awareness in urban warfare. First, an accurate near-ground wave propagation model for indoor and urban scenarios that is based on a hybrid physical optics and asymptotic expansion of dyadic Green's function for a half-space dielectric medium is presented. This model and other full-wave solvers are then used to: 1) investigate direction finding in highly cluttered environments, and 2) analyze the performance of compact antenna diversity systems. Second, a novel sub-wavelength RF source tracking system for applications in GPS-denied environments is realized and measured. The system utilizes a highly miniaturized transmit antenna and a biomimetic circuit that mimics the hearing mechanism of a fly to achieve a compact system. It is shown that tracking with absolute positioning of better than 70cm in complex buildings through multiple layers of walls is achievable from outside in a standoff distance. The third part of the work focuses on a physics-based analysis technique for compact and co-located antenna diversity systems that takes into account the complex radiation pattern of the diversity antennas in conjunction with an accurate near-ground propagation model. A co-located, co-polarized radiation pattern diversity system prototype is realized and characterized. Based on the above analysis technique and measurement results, a diversity gain of 8dB is achieved. In the last part of the work, a subsurface imaging radar system based on distributed near-ground sensor networks that utilize ultra-wideband waveforms in the VHF range is described. Numerical models and laboratory scale model measurements are used to demonstrate high resolution synthetic aperture imaging of deeply submerged targets under a layered medium using an ad hoc network of mobile transceivers.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/96112/1/fikadu_1.pd

The SIMCA algorithm for processing ground penetrating radar data and its practical applications

The main objective of this thesis is to present a new image processing technique to improve the detectability of buried objects such as landmines using Ground Penetrating Radar (GPR). The main challenge of GPR based landmine detection is to have an accurate image analysis method that is capable of reducing false alarms. However an accurate image relies on having sufficient spatial resolution in the received signal. An Antipersonnel mine (APM) can have a diameter as little as 2cm, whereas many soils have very high attenuation at frequencies above 450 MHz. In order to solve the detection problem, a system level analysis of the issues involved with the recognition of landmines using image reconstruction is required. The thesis illustrates the development of a novel technique called the SIMCA (“SIMulated Correlation Algorithm”) based on area or volume correlation between the trace that would be returned by an ideal point reflector in the soil conditions at the site (obtained using the realistic simulation of Maxwell’s equations) and the actual trace. During an initialization phase, SIMCA carries out radar simulation using the system parameters of the radar and the soil properties. Then SIMCA takes the raw data as the radar is scanned over the ground and uses a clutter removal technique to remove various unwanted signals of clutter such as cross talk, initial ground reflection and antenna ringing. The trace which would be returned by a target under these conditions is then used to form a correlation kernel using a GPR simulator. The 2D GPR scan (B scan), formed by abutting successive time-amplitude plots taken from different spatial positions as column vectors,is then correlated with the kernel using the Pearson correlation coefficient resulting in a correlated image which is brightest at points most similar to the canonical target. This image is then raised to an odd power >2 to enhance the target/background separation. The first part of the thesis presents a 2-dimensional technique using the B scans which have been produced as a result of correlating the clutter removed radargram (’B scan’) with the kernel produced from the simulation. In order to validate the SIMCA 2D algorithm, qualitative evidence was used where comparison was made between the B scans produced by the SIMCA algorithm with B scans from some other techniques which are the best alternative systems reported in the open literature. It was found from this that the SIMCA algorithm clearly produces clearer B scans in comparison to the other techniques. Next quantitative evidence was used to validate the SIMCA algorithm and demonstrate that it produced clear images. Two methods are used to obtain this quantitative evidence. In the first method an expert GPR user and 4 other general users are used to predict the location of landmines from the correlated B scans and validate the SIMCA 2D algorithm. Here human users are asked to indicate the location of targets from a printed sheet of paper which shows the correlated B scans produced by the SIMCA algorithm after some training, bearing in mind that it is a blind test. For the second quantitative evidence method, the AMIRA software is used to obtain values of the burial depth and position of the target in the x direction and hence validate the SIMCA 2D algorithm. Then the absolute error values for the burial depth along with the absolute error values for the position in the x direction obtained from the SIMCA algorithm and the Scheers et al’s algorithm when compared to the corresponding ground truth values were calculated. Two-dimensional techniques that use B scans do not give accurate information on the shape and dimensions of the buried target, in comparison to 3D techniques that use 3D data (’C scans’). As a result the next part of the thesis presents a 3-dimensional technique. The equivalent 3D kernel is formed by rotating the 2D kernel produced by the simulation along the polar co-ordinates, whilst the 3D data is the clutter removed C scan. Then volume correlation is performed between the intersecting parts of the kernel and the data. This data is used to create iso-surfaces of the slices raised to an odd power > 2. To validate the algorithm an objective validation process which compares the actual target volume to that produced by the re-construction process is used. The SIMCA 3D technique and the Scheers et al’s (the best alternative system reported in the open literature) technique are used to image a variety of landmines using GPR scans. The types of mines included plastic, wooden and glass ones. In all cases clear images were obtained with SIMCA. In contrast Scheers’ algorithm, the present state-of-the-art, failed to provide clear images of non metallic landmines. For this thesis, the above algorithms have been tested for landmine data and for locating foundations in demolished buildings and to validate and demonstrate that the SIMCA algorithms are better than existing technologies such as the Scheers et al’s method and the REFLEXW commercial software

DETERMINE: Novel Radar Techniques for Humanitarian Demining

Today the plague of landmines represent one of the greatest curses of modern time, killing and maiming innocent people every day. It is not easy to provide a global estimate of the problem dimension, however, reported casualties describe that the majority of the victims are civilians, with almost a half represented by children. Among all the technologies that are currently employed for landmine clearance, Ground Penetrating Radar (GPR) is one of those expected to increase the efficiency of operation, even if its high-resolution imaging capability and the possibility of detecting also non-metallic landmines are unfortunately balanced by the high sensor false alarm rate. Most landmines may be considered as multiple layered dielectric cylinders that interact with each other to produce multiple reflections, which will be not the case for other common clutter objects. Considering that each scattering component has its own angular radiation pattern, the research has evaluated the improvements that multistatic configurations could bring to the collected information content. Employing representative landmine models, a number of experimental campaigns have confirmed that GPR is capable of detecting the internal reflections and that the presence of such scattering components could be highlighted changing the antennas offset. In particular, results show that the information that can be extracted relevantly changes with the antenna separation, demonstrating that this approach can provide better confidence in the discrimination and recognition process. The proposed bistatic approach aims at exploiting possible presence of internal structure beneath the target, which for landmines means the activation or detonation assemblies and possible internal material diversity, maintaining a limited acquisition effort. Such bistatic configurations are then included in a conceptual design of a highly flexible GPR system capable of searching for landmines across a large variety of terrains, at reasonably low cost and targeting operators safety

スパースアレイ・レーダにおける信号処理技術

Tohoku University佐藤源之課