Impulse Ground Penetrating Radar System Research Articles

A low-profile ultra-wideband magneto-electric dipole antenna for ground penetrating radar

ABSTRACT Ultra-wideband antennas that operate at low frequencies usually have a large geometry, which makes them very limited in practical engineering application environment where space is often constrained. In this paper, a novel low-frequency low-profile ultra-wideband magneto-electric (ME) dipole antenna is designed for the application in ground penetrating radar (GPR) to detect deeply buried targets. The antenna is designed at the operation frequency of 230 MHz, so that the objects that are buried as deep as 1.5 m can be detected. Compared to the traditional low-frequency _antennas, it has a profile as low as 740 mm × 140 mm × 150 mm ( 0.49 λ × 0.09 λ × 0.10 λ ). Based on the simulation analysis and validation measurements, the proposed ME dipole antenna has a wide impedance bandwidth for S 11 < − 10 dB from 135 MHz to 382 MHz even when environmental influence is considered. The antenna is further validated with a GPR experiment, where a pipeline with a diameter of about 200 mm at 1200 mm beneath the road surface is successfully detected by an impulse GPR system where the proposed antennas are integrated.

A Low-Complexity and Adaptive Extraction Method for Reflection Hyperbolic Edges in Impulse GPR Images

Traditional Canny edge detection algorithm has been widely used for the extraction of hyperbolic edges in ground penetrating radar (GPR). However, the Canny edge detection algorithm cannot adaptively determine the segmentation thresholds. Moreover, multiple hyperbolic edges are usually detected for each target, which increases the complexity of subsequent processing. In this letter, we propose a novel method that obtains only one hyperbolic edge for each target and automatically determines the segmentation threshold. Both simulation and real data results show that the proposed method is able to extract the target hyperbolic edges precisely and significantly improves the efficiency of target detection combined with the Hough transform in impulse GPR systems.

Characterization of Electromagnetic Properties of In Situ Soils for the Design of Landmine Detection Sensors: Application in Donbass, Ukraine

To design holographic and impulse ground penetrating radar (GPR) sensors suitable for humanitarian de-mining in the Donbass (Ukraine) conflict zone, we measured critical electromagnetic parameters of typical local soils using simple methods that could be adapted to any geologic setting. Measurements were recorded along six profiles, each crossing at least two mapped soil types. The parameters selected to evaluate GPR and metal detector sensor performance were magnetic permeability, electrical conductivity, and dielectric permittivity. Magnetic permeability measurements indicated that local soils would be conducive to metal detector performance. Electrical conductivity measurements indicated that local soils would be medium to high loss materials for GPR. Calculation of the expected attenuation as a function of signal frequency suggested that 1 GHz may have optimized the trade-off between resolution and penetration and matched the impulse GPR system power budget. Dielectric permittivity was measured using both time domain reflectometry and impulse GPR. For the latter, a calibration procedure based on an in-situ measurement of reflection coefficient was proposed and the data were analyzed to show that soil conditions were suitable for the reliable use of impulse GPR. A distinct difference between the results of these two suggested a dry (low dielectric) soil surface, grading downward into more moist (higher dielectric) soils. This gradation may provide a matching layer to reduce ground surface reflections that often obscure shallow subsurface targets. In addition, the relatively high dielectric deeper (10 cm–20 cm) subsurface soils should provide a strong contrast with plastic-cased mines.

Quantitative Stability Analysis of Ground Penetrating Radar Systems

The hardware instability of a ground penetrating radar (GPR) system has a severe impact on the quantitative analysis of GPR data, which is aimed for material characterization and subsurface monitoring. In this letter, an instability index is proposed to quantify the stability performance of a GPR system and the influences of the GPR system type, warm-up time, environmental noise, and the antenna vibration on it are evaluated through a series of laboratory experiments on a sandbox model. It is found that the GPR signal recorded by a stepped-frequency GPR system based on a vector network analyzer is much more stable than that by a commercial impulse GPR system at a cost of more sweep time. A warm-up time of several minutes is enough for an impulse GPR system. Environmental noise has a negligible influence on the stability performance of a GPR system. Mechanical vibrations of GPR antennas have a severe impact on the stability performance of the GPR system, and the instability index and timing jitter can be increased by more than one order of magnitude in a vibrating condition over those in a static condition. The instability index of the direct signal has a negligible difference with that of the reflection signal from a metal plate; thus, a simple measurement of direct signal on the ground surface is suggested for the evaluation of the instability of a GPR system in field in the future.

매설관 주변 지하 공동 탐지를 위한 지하 탐사 레이다의 모의실험

본 논문에서는 지하에 매설된 관 주변에 발생한 지하 공동의 탐지를 위해 지하 탐사 레이다의 가능성을 모의실험으로 조사하였다. 실험 장치는 임펄스형 지하 탐사 레이다 시스템, xy 직교 좌표 로봇, 지하 매질을 채운 탱크, 금속관, 모의실험용 공동 모델로 구현하였다. 특히, 모의실험용 공동 모델은 공기로 채워진 지하 공동의 전기적 특성과 유사하면서 견고한 형상을 유지할 수 있는 스티로폼 ?과 볼을 포장해서 구성하였다. 대표적인 3가지 실험을 통해서 지하 탐사 레이다의 B-scan 자료를 획득하여 2차원 그레이 스케일 영상으로 가시화하였다. B-scan 영상들의 비교를 통해 지하에 매설된 관 주변에 존재하는 지하 공동을 지하 탐사 레이다로 탐지할 수 있음을 보였다. In this paper, a feasibility on a ground-penetrating radar for detecting subsurface cavities near buried pipes has been investigated. The experimental setup was implemented by employing an impulse ground-penetrating radar system, a xy Cartesian coordinate robot, an underground material filled tank, a metal pipe and a simulated cavity model. In particular, the simulated cavity model was constructed by packing Styrofoam chips and balls, which have both similar electrical properties to an air-filled cavity and a solid shape. Through typical three experiments, B-scan data of the radar have been acquired and displayed as 2-D gray-scale images. According to the comparison of B-scan images, we show that the subsurface cavities near the buried pipes can be detected by using the radar survey.

A Novel wideband VHF antenna for impulse GPR applications

A novel wideband VHF antenna for the impulse ground penetrating radar (GPR) system at 200 MHz central frequency is presented in this article. The antenna improves the impulse GPR system for increasing ability penetration. By using the Lemniscate curve, this novel structure of the proposed antenna achieve better radiation than other bow-tie antennas. In addition, this article also proposes the UWB balanced-to-balanced (balun) transformation line is designed to feed the antenna. The balun is an important element for improving the bandwidth of the antenna. The fabrication of the antenna is only simple but also low cost with FR4 substrate and copper patch. The proposed antenna is designed and fabricated with the successful results.

GPR noise reduction based on wavelet thresholdings

Ground-penetrating radar (GPR) is a nondestructive tool, and its data contain information about media beneath the earth's surface. Because of the large bandwidth of the impulse GPR system, the GPR signal is contaminated by the noises coming from various sources. De-noising the GPR signals before performing any data analysis is very important in order to enhance the detection performance of the GPR and to allow accurate layer depth prediction. This paper focuses on de-noising the GPR data by various thresholding rules such as hard, soft, firm shrinkage, and nonnegative garrote thresholding rules. We have decomposed the signal by dual-tree complex wavelet transform (DTCWT) to some coefficients and the shrink ones by various shrinkage rules based on different thresholding functions. For comparison between the results we supply a table which contains the signal-to-noise ratio (SNR) and root-mean-square error (RMSE) of all methods which have been used.

A Novel UWB Sampling Receiver and Its Applications for Impulse GPR Systems

A novel ultrawideband (UWB) synchronous receiver for a UWB radar system is presented. The developed receiver is the first to employ a sampling phase detector, which integrates a step recovery diode and a pair of Schottky diodes, to sample the UWB signal of a radar, enabling the miniaturization of the design. It achieves a 6-GHz sampling bandwidth, a dynamic range of more than 50 dB, and low harmonic distortion of the output baseband signal. The receiver's down-converted IF signals closely match with their original shape, demonstrating its good performance to reconstruct the microwave signals from a receiving antenna. These IF signals can be converted to digital signals by a low-cost A/D. For verification, the performance of the UWB receiver is tested through the experiments of buried steels at different thicknesses in the sand when it is applied to the ground-penetrating radar (GPR). The results show that the GPR system has good horizontal resolution and large detection depth. Therefore, this GPR system is very attractive and effective for applications of short-range and high-resolution detection.

Thickness Measurement of Thin Pavement Layers Using Time-Frequency Analysis of Ground Penetrating Radar Data

Accurate knowledge of pavement layer thickness can provide important information to determine the quality of newly constructed pavements, and to estimate the remaining service life of pavements. Ground penetrating radar (GPR) is one of current technologies for determining pavement layer thickness. However, the estimation of the thickness of very thin pavement layers is not satisfied by the use of commercial impulse GPR. Hence, a thickness measurement approach for very thin layer of multilayered pavement structures is introduced. The technique presented in the present work is based on the evaluation of the instantaneous bandwidth of GPR receiving signals by means of S-transform. One unique feature of the current technique is that it only requires common impulse GPR system operated at relatively low frequency. The algorithms were tested on simulation as well as experimental data. Specific challenges on dispersion effect in dissipative media and random noise effects were also discussed and addressed.

Documenting drainage evolution in Bir Kiseiba, southern Egypt: Constraints from ground‐penetrating radar and implications for Mars

Ground‐penetrating radar (GPR) helps to constrain the origin of relict and largely buried fluvial channels in the Bir Kiseiba region of southern Egypt. Our results indicate that the trunk channel to a tributary system identified in Shuttle Imaging Radar data is incised 10–12 m into bedrock, was southwest draining in its final configuration and laterally migrating toward the northwest, and accentuated relief along the nearby Kiseiba escarpment. Alluvium partially filling the main channel likely reflects effects of increasing aridity and bed load combined with less frequent, flashier precipitation. In contrast to defining channel margins, radar data do not indicate subtle stratigraphic changes in bedding related to fluvial aggradation, but do highlight local reflections likely corresponding to relict alluvial bedforms. Our results support the contention that an impulse GPR system, currently under development, could be deployed on a future Mars rover and assist in defining the regional evolution of the landscape and specific targets for sampling.

Processing and analysis of transient resonant signal of buried object based on wavelet transform

AbstractThe identification of buried objects is one of the challenging and difficult topics in the ground‐penetrating radar (GPR) domain. In this paper, the transient resonant signals from buried perfectly electrical conductors (PECs) are measured by a kind of impulse GPR system. The relationship between the transient resonance and the natural poles of the buried PEC objects is studied. The wavelet transform (WT) method is used to denoise and calculate the instantaneous parameters. The instantaneous WT power and energy spectra of transient resonant signals are calculated and analyzed. The physical mechanism of the resonance of targets is also studied by the singularity expansion method (SEM) theory. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 427–431, 2002.