[go: up one dir, main page]

WO2012161645A1 - Système radar de sondage du sol comprenant un détecteur magnétorésistant - Google Patents

Système radar de sondage du sol comprenant un détecteur magnétorésistant Download PDF

Info

Publication number
WO2012161645A1
WO2012161645A1 PCT/SE2012/050543 SE2012050543W WO2012161645A1 WO 2012161645 A1 WO2012161645 A1 WO 2012161645A1 SE 2012050543 W SE2012050543 W SE 2012050543W WO 2012161645 A1 WO2012161645 A1 WO 2012161645A1
Authority
WO
WIPO (PCT)
Prior art keywords
radar signal
ground penetrating
signal
receiver
dipole antenna
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/SE2012/050543
Other languages
English (en)
Other versions
WO2012161645A8 (fr
Inventor
Anders Persson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO2012161645A1 publication Critical patent/WO2012161645A1/fr
Publication of WO2012161645A8 publication Critical patent/WO2012161645A8/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/12—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with electromagnetic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • G01R33/098—Magnetoresistive devices comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/885—Radar or analogous systems specially adapted for specific applications for ground probing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices

Definitions

  • the present invention relates to a ground penetrating radar (GPR) system.
  • GPR ground penetrating radar
  • the stratigraph ical information that can be derived from an electromagnetic GPR system is difficu lt to interpret, since almost every change in material , density, humidity, etc. will give rise to an echo. Even though the result is rich in information , the interpretation of it is difficult and interesting features can often be hidden by uninteresting ones. Often , a high ly skilled and experienced expert is required to interpret the data.
  • the different relative dielectric permittivity of air and soils causes part of the transmitted signal to be reflected directly off the surface of the ground .
  • resonances in the transmitting and receiving antennas create ringing effects that taint the detected signal.
  • An object of the present invention is therefore to provide a GPR system which in at least some aspect overcomes the drawbacks present in common GPR systems. This object is ach ieved by a GPR system according to claim 1 . Another object of the present invention is to provide a simplified and in at least some aspect improved method of detecting a feature in the ground . This object is achieved by a method accord ing to claim 8.
  • the ground penetrating radar system comprises a transmitter for generating and transmitting a radar signal and a receiver for receiving a radar signal .
  • the transmitter comprises a signal generator and at least one magnetic dipole antenna.
  • the system is characterized in that the receiver comprises at least one magnetoresistive sensor. Since the GPR system accord ing to the present invention uses a magnetoresistive sensor for signal detection instead of a resonant antenna, the bandwidth is increased so that signals from kilo- u p to gigahertz frequencies can be detected . This enables both time and frequency domain analysis of the relative permittivity and magnetic permeability of the materials in the investigated volume. Moreover, the magnetoresistive sensor is not based on resonance and is therefore not subjected to interference, ringing or cou pling to the transmitting antenna. Using a magnetoresistive sensor, the receiver may also be min iaturized .
  • the shield is comprised in the magnetic dipole antenna.
  • the GPR system is configured to operate in the magnetic near- field regime.
  • the data is easier to interpret than data from a common GPR system relying on the electric components of radar signals. Additionally, better ground penetration is achieved and problems related to signal reflection off the air-soil interface are avoided .
  • the magnetic dipole antenna is a shielded loop antenna.
  • the GPR system according to this embodiment is operated in the magnetic near- field regime.
  • the shield is comprised in the receiver. In th is embod iment, the electric field component is removed at the receiver. This enables detection of signals arising from far-field interaction of the radar signal with a feature.
  • the magneto- resistive sensor is a sensor based on anisotropic magneto- resistance, the planar Hall effect, giant magnetoresistance, or tunnelling magnetoresistance.
  • a sensor based on anisotropic magnetoresistance offers a low noise level.
  • a sensor based on the planar Hall effect offers a low noise level and also a high linearity.
  • a sensor based on giant magnetoresistance offers a large dynamic range, while a sensor based on tunnelling magnetoresistance offers a strong signal .
  • the magneto- resistive sensor comprises magnetoresistive sensing elements configured in a Wheatstone bridge. This embod iment offers a high signal-to-noise ratio, and an improved thermal stability.
  • a further step of removing an electric field component from the transmitted and/or the reflected radar signal is added .
  • the magnetic dipole antenna is operated in continuous mode. In this embodiment, target detection in the magnetic near-field regime is simplified . According to another embod iment of the second aspect of the present invention , the magnetic dipole antenna is operated in pulse mode. In this embod iment, more advanced time and frequency domain analysis can be performed .
  • FIG. 1 is a schematic illustration of the GPR system accord ing to the invention .
  • the ground penetrating radar (GPR) system is schematically shown in figure 1 .
  • the GPR system 1 comprises a transmitter 2 and a receiver 3.
  • the transmitter comprises a signal generator 4 and one or more magnetic dipole antennas 5.
  • the receiver comprises one or more magnetoresistive sensors.
  • the receiver is connected to an amplifier 6 and a data acquisition unit 7.
  • a radar signal 8 is generated by the signal generator 4.
  • the radar signal is transmitted by the magnetic dipole antenna 5 towards that medium.
  • the transmitted radar signal is then reflected on interfaces between materials within the medium with different magnetic permeability and/or different relative permittivity.
  • the reflected signal is detected by the magnetoresistive sensors comprised in the receiver 3 as a variation in magnetic field strength and/or direction .
  • an outgoing signal from the sensor is amplified by the amplifier 6 and passed on to the data acquisition unit 7 for further analysis.
  • a radar image of an iron disc with a diameter of 27 cm, buried in the ground at a depth of 1 m, which was acquired using a GPR system according to the present invention is shown in figure 2.
  • the magnetoresistive sensor used for detecting the reflected radar signal comprises sensing elements with a resistance dependent on the magnetic field strength , direction and/or variation .
  • the magnetoresistive sensor used in the present invention may for example be a sensor based on anisotropic magnetoresistance (AMR), the planar Hall effect (PHE), giant magnetoresistance (GMR), or tunnelling magnetoresistance (TMR).
  • AMR anisotropic magnetoresistance
  • PHE planar Hall effect
  • GMR giant magnetoresistance
  • TMR tunnelling magnetoresistance
  • the magnetoresistive sensor is comprised of several sensing elements, which sensing elements can be magnetic tunnel junctions or spin valves.
  • the sensing elements are arranged on a substrate so as to form a Wheatstone bridge comprising four branches. Two branches may be magnetically shielded in order to serve as reference resistances, while the two non-shielded branches serve as sensing branches.
  • Each branch may comprise several sensing elements connected in parallel and/or series in order to optimize the signal-to-noise ratio.
  • a common factor for all mentioned magnetoresistive sensors is that they do not rely on resonances with the transmitting antenna. This factor renders the detected signal from the GPR system according to the invention more stable than signals from a common GPR system based on resonances between a transmitting and a receiving antenna.
  • the sensor is not subjected to interferences, ringing or coupling to the transmitting antenna, and the output data from the receiver is therefore much easier to interpret.
  • the antenna should be a magnetic dipole antenna, which may or may not be shielded to remove the electric field component from the transmitted radar signal.
  • a shield is included in the antenna, such as in a shielded loop antenna.
  • the shield in the antenna removes the electric field component from the transmitted radar signal and consequently, only the magnetic field component of the radar signal interacts with the material of the solid or liquid medium. Since the signal has no electric field component, it is only reflected on interfaces between materials with different magnetic permeability, and consequently, no signals resulting from dielectric reflections are detected by the receiver.
  • the output data from the receiver is less rich in information than data from a common GPR system relying on dielectric reflections, but on the other hand, much easier to interpret.
  • a shielded antenna for signal transmission in the GPR system means that the system is configured to work in the magnetic near-field region, or at a distance from the antenna corresponding to a maximum of about 2 ⁇ , where A is the wavelength of the transmitted radar signal. Operation in the magnetic near-field region enables better penetration into most liqu id or solid mediums than in a common GPR system, since the entire signal is transmitted into the med ium, given that the med ium has the same magnetic permeability as the atmosphere in which the transmitter is located .
  • the GPR system according to th is embodiment thereby avoids problems related to the electrical signal being reflected off e.g . an air-soil interface as a consequence of different relative dielectric permittivity of air and soil .
  • the GPR system according to the present invention can be operated in either continuous mode or pulse mode.
  • continuous mode a feature is identified by studying the standing wave pattern between the transmitting antenna and the receiver. This mode is particularly useful for basic target detection and is carried out in the magnetic near-field region .
  • a distance to the feature may be determined by transmitting radar signals of at least three orthogonal frequencies.
  • pulse mode the distance to the feature is determined by measuring the time delay from transmitting the radar signal to receiving the reflected signal.
  • the pulse mode enables more advanced time and frequency analysis than the continuous mode, and can also be used for detecting features in the electromagnetic far-field region .
  • the antenna may also be a different kind of magnetic dipole antenna, such as a spiral antenna.
  • the receiver will, in addition , detect electromagnetic far-field reflections, and hence materials with different dielectric permittivity.
  • a shield may instead be included in the sensor to prevent false signals from arising as a result of interaction of these far-field reflections with electronics surround ing the sensor.

Landscapes

  • Physics & Mathematics (AREA)
  • Remote Sensing (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Electromagnetism (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geophysics (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

L'invention concerne un système radar de sondage du sol (GPR) (1) et un procédé de détection d'un élément (9) intégré dans un milieu solide ou liquide (10) à partir de l'extérieur de ce milieu. Le système GPR comprend un émetteur (2) permettant de générer et de transmettre un signal radar (8) vers le milieu solide ou liquide comprenant l'élément, et un récepteur (3) permettant de recevoir le signal radar après une réflexion sur l'élément, l'émetteur comprenant un générateur de signal (4) et au moins une antenne dipôle magnétique (5). Le récepteur comprend au moins un détecteur magnétorésistant, qui est utilisé pour détecter le signal radar réfléchi.
PCT/SE2012/050543 2011-05-20 2012-05-18 Système radar de sondage du sol comprenant un détecteur magnétorésistant Ceased WO2012161645A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE1150476A SE536435C2 (sv) 2011-05-20 2011-05-20 Markpenetrerande radarsystem innefattande minst en magnetoresistiv sensor
SE1150476-8 2011-05-20

Publications (2)

Publication Number Publication Date
WO2012161645A1 true WO2012161645A1 (fr) 2012-11-29
WO2012161645A8 WO2012161645A8 (fr) 2013-06-27

Family

ID=47217506

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2012/050543 Ceased WO2012161645A1 (fr) 2011-05-20 2012-05-18 Système radar de sondage du sol comprenant un détecteur magnétorésistant

Country Status (2)

Country Link
SE (1) SE536435C2 (fr)
WO (1) WO2012161645A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140125508A1 (en) * 2011-11-21 2014-05-08 Stolar Research Corporation Large area ground monitoring
US8912943B2 (en) * 2011-12-05 2014-12-16 AMI Research & Development, LLC Near field subwavelength focusing synthetic aperture radar with chemical detection mode

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109632362A (zh) * 2018-12-17 2019-04-16 山东农业大学 一种土壤湿润体体积获取方法、系统及装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000025385A1 (fr) * 1998-10-26 2000-05-04 Emc Automation, Inc. Antenne a large bande integrant a la fois des elements rayonnants dipolaires electriques et magnetiques
GB2411729A (en) * 2004-03-01 2005-09-07 Pathfinder Energy Services Inc Azimuthally sensitive receiver array for an electromagnetic measurement tool
WO2010101630A1 (fr) * 2009-03-03 2010-09-10 Iii Herbert Duvoisin Détection d'objets de surface et enterrés

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000025385A1 (fr) * 1998-10-26 2000-05-04 Emc Automation, Inc. Antenne a large bande integrant a la fois des elements rayonnants dipolaires electriques et magnetiques
GB2411729A (en) * 2004-03-01 2005-09-07 Pathfinder Energy Services Inc Azimuthally sensitive receiver array for an electromagnetic measurement tool
WO2010101630A1 (fr) * 2009-03-03 2010-09-10 Iii Herbert Duvoisin Détection d'objets de surface et enterrés

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
BELLETT ET AL.: "An investigation of magnetic antennas for ground penetrating radar", PROGRESS IN ELECTROMAGNETICS RESEARCH, vol. 43, 2003, pages 257 - 271 *
BELLETT ET AL.: "Electrically small magnetic GPR antennas", IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM, 2003 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140125508A1 (en) * 2011-11-21 2014-05-08 Stolar Research Corporation Large area ground monitoring
US9207307B2 (en) * 2011-11-21 2015-12-08 Stolar, Inc. Large area ground monitoring
US8912943B2 (en) * 2011-12-05 2014-12-16 AMI Research & Development, LLC Near field subwavelength focusing synthetic aperture radar with chemical detection mode

Also Published As

Publication number Publication date
WO2012161645A8 (fr) 2013-06-27
SE1150476A1 (sv) 2012-11-21
SE536435C2 (sv) 2013-10-29

Similar Documents

Publication Publication Date Title
US6559645B2 (en) Detector apparatus and method
Slob et al. Ground-Penetrating Radar: Surface and borehole ground-penetrating-radar developments
US8723723B2 (en) Dual mode ground penetrating radar (GPR)
US10371853B2 (en) Nuclear magnetic resonance system with feedback induction coils
US8680865B2 (en) Single well reservoir imaging apparatus and methods
CA2642633C (fr) Procede electromagnetique sur eaux peu profondes utilisant une source regulee
JP6567162B2 (ja) 地下物性探査システムおよびそれを用いた地下物性分析方法
AU2011100086A4 (en) A method for measuring biomass of tree-roots by ground-penetrating radar
US20120291556A1 (en) Long Baseline Navigation System
Radzevicius et al. Pitfalls in GPR data interpretation: differentiating stratigraphy and buried objects from periodic antenna and target effects
Saito et al. Estimating infiltration front depth using time-lapse multioffset gathers obtained from ground-penetrating-radar antenna array
JP5568237B2 (ja) 三次元位置推定システム、及び、ダイポールアレイアンテナ
WO2012161645A1 (fr) Système radar de sondage du sol comprenant un détecteur magnétorésistant
CN104655656A (zh) 基于宽频磁波透射模型参数辨识的检测成像方法与装置
KR101551824B1 (ko) 매설물 탐지 레이더 및 탐지 방법
JP2018063245A (ja) 比誘電率の決定方法及び地中埋込物体の検出方法
RU2335780C1 (ru) Способ дистанционного обнаружения и идентификации вещества
Capizzi et al. GPR multi‐component data analysis
Kang et al. The effect of directivity of antenna for the evaluation of abnormal area using ground penetrating radar
Redman et al. Measurement of bulk electrical properties using GPR with a variable reflector
Peden et al. A scale-model study of down-hole VHF dipole arrays with application to subsurface exploration
Ma et al. Electromagnetic wave transmission characteristics research of single-borehole radar
Pallavi et al. Estimating depth of influence of GPR ground wave in lysimeter experiment
RU125352U1 (ru) Система пространственной фильтрации для геоэлектроразведки
Li et al. Dual-polarized RF Tags for Orientation Estimation of Underground Pipelines

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12790191

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12790191

Country of ref document: EP

Kind code of ref document: A1