Industrial radar sensor arrays and their applications
description
Transcript of Industrial radar sensor arrays and their applications
RFMTC11GÄVLE OCTOBER 4–5th 2011
Industrial radar sensor arrays and their applications
October 04, 2011
P. Vainikainen, V. Mikhnev, Ye. Maksimovitch, M.-K. OlkkonenAalto University School of Electrical Engineering
SMARAD Dept. of Radio Science and EngineeringP.O. Box 13000, FI-00076 AALTO Finland
Outline
• Wideband technologies• UWB antennas and antenna arrays• Signal processing techniques• Experimental examples• Summary
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Wideband technologies• 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
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Tapered-slot UWB antenna
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Antenna width 120 mmAntenna length 230 mm
Substrate FR-4R-cards 200 Ω/
Elliptical form of flares
Width of microstrip 1.8 mm stub length 10 mm
Slotline width 0.5 mmstub length 13 mm
The both stubs are circular 85º sectors.
R-cards
Tapered-slot UWB antenna
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-150 -100 -50 0 50 100 150
-40
-30
-20
-10
0
10
solid flares
corrugated edges
corrugated edges and R-cards
Angle, [deg]
Ga
in, d
B
E-plane
Unloaded antenna
Loaded antenna
E-field
Tapered-slot UWB antenna
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0 1 2 3 4 5 6 7 Frequency [GHz]
-10
-5
0
5
10
15
Gai
n V
SW
R
wsvr 0
5
10
15
UWB antenna arrays
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direction of scan
transmitting antenna
receiving antenna
Double-ladder Zigzag array array
3 cm
UWB antenna arrays
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H–V V–H
V–V H–H
G. Alli et al, “Data processing for mine-detection polarimetric ground penetrating radar array,” in Proc. of the 10th Int. Conf. on Ground Penetrating Radar, 2004, Delft, 4p.
Signal processing
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Two subtasks of interest:•Detection of reflecting targets by the sensor•Evaluation of parameters of the target and its discrimination
Signal component
...........................
Time-frequency analysis
Natural complex resonances
Wigner-Ville transform
Evaluation and discrimination
Set of features
Signal processingfor the case of GPR
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Extraction of amplitude vs time
Extraction of phase vs time
Removal of the phase due propagation
Intensity of pixel
Color of pixel
B-SCAN
Phase profile retrieval
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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
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.
cLtffitXanglet 2exp 21
Building GPR image
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90
180 0
270
B-scan in phase
Image
B-scan in amplitude Threshold
Final image
Color map
Experimental results
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Experimental setup:
• Network analyzer Agilent E5071B
• Frequency range 1.3 – 6.5 GHz
• Tapered-slot antennas
T-R antenna pair
Network analyzer
Conventional grayscale image Pure phase image Amplitude-phase image
Metal rods
In sand
Experimental results
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De
pth
[cm
]
0 10 20 30 40 50
0
10
20
30
40
Distance along track [cm]
De
pth
[cm
]
10 20 30 40 50
0
10
20
30
40
Void in sand PMN mine simulant in sand
Metal rod (orthogonal polarization) Plastic pipe (parallel polarization)
Summary• 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.
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