System for exploring underground geophysical properties and method for analyzing underground geophysical properties using the same

Patent metadata

Field	Value
Publication number	US-10101489-B2
Application number	US-201615521477-A
Country	US
Kind code	B2
Filing date	Jun 30, 2016
Priority date	Aug 14, 2015
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

The present invention relates to an apparatus and method for analyzing underground geophysical properties using the principle of a ground-penetrating radar. In order to resolve problems of the ground-penetrating radar (GPR) techniques of the related art which mainly acquires an underground image using electric field reflected waves and excludes acquisition of an underground image using magnetic field reflected waves, the present invention provides a system for exploring underground geophysical properties and a method for analyzing underground geophysical properties using the same, the system including: a transmission antenna which is located in a specific spot on the ground and radiates an electromagnetic pulse signal; and a pair of reception antennae which measures an electric field signal and a magnetic field signal which are generated by the radiated signal, in which the system is configured to be able to acquire not only underground images using electric field reflected waves as in technology of the related art but also underground images using magnetic field reflected waves, thereby exploring underground geophysical properties more accurately and effectively than conventional technology.

First claim

The invention claimed is:

1. An underground geophysical property exploring system comprising:
at least one transmission antenna configured to radiate an electromagnetic wave pulse signal;
at least one pair of an electric field signal reception antenna and a magnetic field signal reception antenna, the electric field signal reception antenna configured to measure an electric field signal generated by the electromagnetic wave pulse signal radiated from the transmission antenna, the magnetic field signal reception antenna configured to measure a magnetic field signal generated by the electromagnetic wave pulse signal radiated from the transmission antenna;
an analysis unit configured to analyze geophysical properties of an underground medium based on the electric field signal measured by the electric field signal reception antenna and the magnetic field signal measured by the magnetic field signal reception antenna; and
a control unit configured to control an entire operation of the system,
wherein when the transmission antenna is provided on ground, and the electric field signal reception antenna and the magnetic field signal reception antenna receive the electric field and the magnetic field generated by the electromagnetic wave pulse signal radiated from the transmission antenna, respectively,
the electric field {right arrow over (e)} and the magnetic field {right arrow over (h)} is represented by Equation (1) below,
{right arrow over (e)} ={right arrow over ( r e )}⊗{right arrow over ( g ee )}⊗ {right arrow over (j)},{right arrow over (h)} ={right arrow over ( r h )}⊗{right arrow over ( g he )}⊗ {right arrow over (j)}    (1)

(Here, {right arrow over (j)} represents the electromagnetic wave pulse signal, {right arrow over (g)} represents an underground geophysical property system characteristic as an impulse response, {right arrow over (r e )} represents a reception function of the electric field signal reception antenna, and {right arrow over (r h )} represents a reception function of the magnetic field signal reception antenna),
the Equation (1) is Fourier transformed in a frequency domain to be Equation (2) below,
{right arrow over (E)} ={right arrow over ( R e )}{right arrow over ( G ee )} {right arrow over (J)},{right arrow over (H)} ={right arrow over ( R h )}{right arrow over ( G he )} {right arrow over (J)}    (2), and

a ratio of the electric field and the magnetic field is calculated using Equation (3) below,
{right arrow over (Z)}={right arrow over (E)}/{right arrow over (H)} =({right arrow over ( R e )}{right arrow over ( G ee )})/({right arrow over ( R h )}{right arrow over ( G he )})   (3), and

wherein when the electric field signal and the magnetic field signal generated by the electromagnetic wave pulse signal radiated from the transmission antenna are measured in air by the electric field signal reception antenna and the magnetic field signal reception antenna, and a ratio |{right arrow over (E air )}|/|{right arrow over (H air )}| of intensities of the electric field and the magnetic field in the air is defined as an intrinsic impedance,
a calibration function {right arrow over (ƒ(ω) )} is calculated based on the intrisic impedance using equation (4) below and is used to calibrate the ratio of the intensities of the electric field signal and the magnetic field signal to have a constant property regardless of a frequency when the transmission antenna, the electric field signal reception antenna, and the magnetic field signal reception antenna are used in vacuum or in the air,

f
⁡

(
ω
)

→

=

η
o

E

meas
,
air

→

/

H

meas
,
air

→

=

R

h
′

→

R

e
′

→

,

(
4
)

(Here, {right arrow over (R h′ )} represents a reception function of the magnetic field signal reception antenna, {right arrow over (R e′ )} represents a reception function of the electric field signal reception antenna, and η o represents the intrinsic impedance).

2. The system according to claim 1 , wherein the transmission antenna is an antenna configured to radiate an ultra broadband electric wave pulse.

3. The system according to claim 1 , wherein the electric field signal reception antenna is configured as a dipole antenna, in which two conductive radiators are disposed in parallel with respect to a power feeding point to receive an ultra broadband pulse signal.

4. The system according to claim 1 , wherein the magnetic field signal reception antenna is configured as a loop antenna around which a single conductive radiator is wound to receive an ultra broadband pulse signal.

5. The system according to claim 1 , wherein the system is configured to obtain the calibration function with regard to a medium other than the air using the the equation (4).

6. The system according to claim 1 , wherein the geophysical properties of the underground medium are obtained using Equation (5),

Z

meas
,
gnd

→

=

Assignees

• Korea Inst Geoscience & Mineral Resources

Inventors

• Kang Woong
• Kim Jung Ho
• Yi Myeong Jong
• Papadopoulos Nikos

Classifications

• G01V3/12 Primary

  operating with electromagnetic waves {(operating with millimetre waves G01V8/005)} · CPC title

• G01S13/885

  for ground probing (prospecting or detecting using electromagnetic waves G01V3/12) · CPC title