1. RFMTC11 GÄVLE OCTOBER 4–5th 2011 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

2. RFMTC11 Outline Wideband technologies UWB antennas and antenna arrays Signal processing techniques Experimental examples Summary 2011-10-04

3. RFMTC11 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 2011-10-04

4. RFMTC11 Tapered-slot UWB antenna 2011-10-04 Antenna width120 mm Antenna length230 mm SubstrateFR-4 R-cards 200 Ω/□ Elliptical form of flares Width of microstrip 1.8 mm stub length 10 mm Slotline width 0.5 mm stub length 13 mm The both stubs are circular 85º sectors. R-cards

5. RFMTC11 Tapered-slot UWB antenna 2011-10-04 E-plane Unloaded antenna Loaded antenna E-field

6. RFMTC11 Tapered-slot UWB antenna 2011-10-04

7. RFMTC11 UWB antenna arrays 2011-10-04 direction of scan transmitting antenna receiving antenna Double-ladder Zigzag array array 3 cm

8. RFMTC11 UWB antenna arrays 2011-10-04 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.

9. RFMTC11 Signal processing 2011-10-04 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

10. RFMTC11 Signal processing for the case of GPR 2011-10-04 Extraction of amplitude vs time Extraction of phase vs time Removal of the phase due propagation Intensity of pixel Color of pixel B-SCAN

11. RFMTC11 Phase profile retrieval 2011-10-04 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.

12. RFMTC11 Building GPR image 2011-10-04 90 180 0 270 B-scan in phase Image B-scan in amplitude Threshold Final image Color map

13. RFMTC11 Experimental results 2011-10-04 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

14. RFMTC11 Experimental results 2011-10-04 Void in sand PMN mine simulant in sand Metal rod (orthogonal polarization) Plastic pipe (parallel polarization)

15. RFMTC11 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. 2011-10-04