GPR systems work by sending a tiny pulse of energy into a material via an antenna. An integrated computer records the strength and time required for the return of any reflected signals. Subsurface variations will create reflections that are picked up by the system and stored on digital media. These reflections are produced by a variety of material such as geological structure differences and man-made objects like pipes and wire.

1. Seminar presentation
on
“GROUND PENETRATING RADAR”

2. Contents:
1. Introduction
2. Components of GPR
3. GPR working principle
4. Reflected signal
5. GPR depth determination
6. How deep can GPR go into ground?
7. GPR received signal and graphic profile display
8. Advantages
9. Applications
10. Conclusion
11. References

3. Introduction:
RADAR → Radio Detection and Ranging.
Detect target in free space
Determine the range
Ground-penetrating radar (GPR) is a geophysical method
that uses radar pulses to image the subsurface.
GPR finding and detecting buried object.
GPR can be used in a variety of media, including rock,
soil, ice, fresh water, pavements and structures. It can
detect objects, changes in material, and voids and cracks.
Probing into soil to detect pipelines and tanks and detect
thickness of soil.

4. Components of GPR:
1. Transmitting
and receiving
unit
2. Control unit
3. Display unit
4. Power
supplies

5. GPR Working Principle:
An EM pulse is sent
through an antenna,
penetrating into the
surveyed material.
A portion of the
energy is reflected
back to the antenna
when an interface
between materials of
dissimilar dielectric
constant is
encountered.

6. Reflected Signal:
The amount of reflected
energy at an interface is
governed by:
 

r r
 
1 2

r r
1 2

1,2

where ρ1,2 is the
reflection coefficient
and εr1 and εr2 are the
dielectric constants.
Typical Dielectric Constants:
Material Relative
permittivity
Air 1
Asphalt: dry 2-4
Clay 2-40
Dry sand 3-5
Concrete: dry 4-10
Fresh water 80
Metals ∞

7. GPR Depth Determination:
The reflected signal
has information on:
how quickly
the signal traveled
how much was
attenuated
These quantities
depend on spatial
configuration and
materials.
The depth of a layer is given by:
D = (5.9t)/sqrt. of(Er)
D = depth of target (inch.)
t = wave travel time (nanosecond)
5.9 = a constant incorporating speed of
light and unit conversions
Er = dielectric constant of subsurface
material

8. How deep can GPR go into
ground?:
It depend upon two
condition:
 The type of soil or rock in
the GPR survey area.
 The frequency of the
antenna used.
 Low frequency systems are
more penetrating but data
resolution is lower.
 High frequency systems
have limited penetration but
offer a much higher
resolution.
Antenna
Frequency
Maximum
Penetration
Depth
Appropriate
Application
1500 MHz 0.5 m
Rebar mapping
and concrete
evaluation.
900 MHz 1 m
Pipe and void
detection or
assessing concrete
thickness.
400 MHz 4 m
Utility surveys,
pavement
evaluation, storage
tank detection and
assessing
structural integrity
270 MHz 6m
Utility surveys,
geology and
archaeology

9. GPR Received signal and graphic
profile display:

10. Advantages:
Extremely accurate
Fast
Not needed to drilling and digging selected area
Real time targeting
Non-destructive
Non-intrusive
Digital media storage
Easy to operate
Safe

11. Applications:
In the Earth sciences it is used to study bedrock, soils,
groundwater, and ice.
Military uses include detection of mines, unexploded
ordnance, and tunnels.
locating clandestine graves and buried evidence.
the other main applications for ground penetration radars
to locate underground utilities.

12. Conclusion:
GPR has been developed into a sophisticated
technique that can provide detailed images of the near
surface. As opposed to other locating techniques that are
capable of detecting only metallic or conductive utilities
and underground targets, GPR can locate and characterize
both metallic and non-metallic subsurface features. It is
completely non-intrusive, non-destructive and safe.

13. References :
vashov, S. I.; Razevig, V. V.; Vasiliev, I. A.; Zhuravlev, A. V.; Bechtel, T. D.;
Capineri, L. (2011). "Holographic Subsurface Radar of RASCAN Type:
Development and Application". IEEE Journal of Selected Topics in Applied Earth
Observation and Remote Sensing 4 (4): 763–778.
doi:10.1109/JSTARS.2011.2161755. Retrieved 26 September 2013.
ETSI EG 202 730 V1.1.1 (2009–09), "Electromagnetic compatibility and Radio
spectrum Matters (ERM); Code of Practice in respect of the control, use and
application of Ground Probing Radar (GPR) and Wall Probing Radar (WPR)
systems and equipment
Wilson, M. G. C.; Henry, G.; Marshall, T. R. (2006). "A review of the alluvial
diamond industry and the gravels of the North West Province, South Africa". South
African Journal of Geology (Geological Society of South Africa) 109 (3): 301–314
Daniels DJ (ed.) (2004). Ground Penetrating Radar (2nd ed.). Knoval (Institution of
Engineering and Technology). pp. 1–4. ISBN 978-0-86341-360-5