RFMTC11
Industrial radar sensor arrays and
their applications
October 04, 2011
P. Vainikainen, V. Mikhnev, Ye. Maksimovitch, M.-K. Olkkonen
Aalto University School of Electrical Engineering
SMARAD Dept. of Radio Science and Engineering
P.O. Box 13000, FI-00076 AALTO Finland
valeri.mikhnev@aalto.fi
RFMTC11
GÄVLE OCTOBER 4–5th 2011
Outline
RFMTC11
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•
•
•
•
2011-10-04
Wideband technologies
UWB antennas and antenna arrays
Signal processing techniques
Experimental examples
Summary
Wideband technologies
RFMTC11
• Impulse technology
– georadar
– subsurface radar
– level gauges
• Frequency-swept sine-wave technology
–
–
–
–
–
moisture sensors
level gauges
thickness gauges
sensors for material characterization
anti-collision radar
• M-sequence technology
– attempts to combine advantages of the both technologies above
– very high speed of data acquisition
2011-10-04
Tapered-slot UWB antenna
RFMTC11
R-cards
Antenna width
Antenna length
120 mm
230 mm
Substrate
R-cards
FR-4
200 Ω/□
Elliptical form of flares
Width of microstrip
stub length
1.8 mm
10 mm
Slotline width
stub length
0.5 mm
13 mm
The both stubs are circular 85º sectors.
2011-10-04
Tapered-slot UWB antenna
E-field
RFMTC11
E-plane
10
solid flares
Gain, dB
0
Unloaded
antenna
-10
corrugated
edges
-20
-30
corrugated edges
and R-cards
-40
-150
-100
-50
0
50
Angle, [deg]
2011-10-04
100
150
Loaded
antenna
Tapered-slot UWB antenna
15
10
10
5
5
0
0
-5
-10
0
2011-10-04
1
2
3
4
5
Frequency [GHz]
6
7
VSWR
15
wsvr
Gain
RFMTC11
UWB antenna arrays
RFMTC11
Double-ladder
array
Zigzag
array
3 cm
direction of scan
transmitting antenna
receiving antenna
2011-10-04
UWB antenna arrays
RFMTC11
2011-10-04
V–V
H–H
H–V
V–H
G. Alli et al, “Data processing for minedetection polarimetric ground
penetrating radar array,” in Proc. of the
10th Int. Conf. on Ground Penetrating
Radar, 2004, Delft, 4p.
Signal processing
RFMTC11
Two subtasks of interest:
• Detection of reflecting targets by the sensor
• Evaluation of parameters of the target and its discrimination
Evaluation and
discrimination
Signal component
Time-frequency analysis
Natural complex
resonances
Wigner-Ville transform
...........................
2011-10-04
Set of features
RFMTC11
Signal processing
for the case of GPR
Extraction of
amplitude vs time
Intensity of pixel
B-SCAN
Color of pixel
Extraction of phase
vs time
2011-10-04
Removal of the phase
due propagation
Phase profile retrieval
RFMTC11
1. Determination of dominant peak by magnitude in every A-scan and
its filtering by the one-dimensional Gaussian filter yielding partial
range profile by amplitude.
2. Derivation of the phase profile corresponding to the peak using
t   angleX t   exp i f1  f 2 t  2L c 
where L is position of the peak.
3. Calculation of the residual of the signal after subtracting the filtered
dominant peak.
4. Return to the step 1 until given number of peaks is reached or all
peaks above given threshold are processed.
5. Summing up obtained profiles. Derivation of both amplitude and
phase versus time.
2011-10-04
Building GPR image
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Color map
90
B-scan in
phase
180
0
Image
270
B-scan in
amplitude
Threshold
Final image
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Experimental results
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Network analyzer
Experimental setup:
T-R antenna pair
Metal rods
In sand
Conventional grayscale image
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Pure phase image
•
Network analyzer Agilent E5071B
•
Frequency range 1.3 – 6.5 GHz
•
Tapered-slot antennas
Amplitude-phase image
Experimental results
RFMTC11
Metal rod (orthogonal polarization)
Plastic pipe (parallel polarization)
0
0
10
10
20
20
30
30
40
40
0
2011-10-04
PMN mine simulant in sand
Depth [cm]
Depth [cm]
Void in sand
10
20
30
Distance along track [cm]
40
50
10
20
30
Distance along track [cm]
40
50
Summary
RFMTC11
• A modified UWB tapered-slot antenna exhibiting high wideband
gain and low level of sidelobes has been developed.
• A novel microwave imaging method based on separate
determination and representation of amplitude and phase profiles
has been proposed.
• Subsurface objects can be detected by amplitude and
discriminated by phase in a common color image.
• The retrieval of the phase profile can be applied to other tasks of
microwave sensing. So, air gaps between shotcrete and rocks in
tunnels can be detected and recognized by this method.
2011-10-04