c

R/

Output of matched filter at R2 (Reflection echo)

c

R/

Output of matched filter at R1 (Transmissive echo)

-1 0 11

1.5

2

2.5

3

3.5

4

x/

z/

Permittivity and Internal Image Estimation

Accurate Image Expansion Method for Target Buried inDielectric Medium Using Multi-static UWB Radar

Toshiki Manaka1, Shouhei Kidera2 and Tetsuo Kirimoto2

1 Graduate School of Bioengineering, The University of Tokyo, Japan2 Graduate School of Informatics and Engineering, The University of Electro-Communications, Japan

Email: kidera@ee.uec.ac.jp

RMSE[λ] Estimated permittivity

Relative error of permittivity [%]

Before WC 5.83×10-2 8.56 5.6After WC 3.90×10-2 8.84 2.8

Microwave UWB Radar・Non-invasive bio-imaging ・Non-destructive testing for detecting crack of wallGeneral drawback: Spatial resolution or accuracy for internal image is not sufficient for target identification

・Dielectric media: Cement ( =9.07)・Buried object: Aluminum cylinder ・Frequency range : 1.0 GHz – 3.0GHz (10MHz interval)・Range resolution in air: 75 mm・Num. of scanning samples: 101

Results in Experiment・One transmitting antenna : Tx・Two receiving antennas : R1 and R2

R1: Transmissive echoR2: Reflection echo from

outer and inner dielectric medium

・Dielectric medium: Homogeneous ・Dielectric object is rotated along ・Transmitted waveform: Mono-cycle pulse (center wavelength : λ )

System Model

Creeping Wave Suppression Method

RPM(Range Points Migration) based internal imaging method(K. Akune, S. Kidera and T. Kirimoto, IEICE Trans. on Electronics, Aug., 2012)

Accurate internal imaging method

Introduction

Requirement: Need for combining with permittivity estimation method

Objective: Permittivity and internal image estimation method with FDTD based waveform compensation

x/

y/

Creeping path

Cement

27.8cm

5cm

Aluminum

Outer boundary estimation : Original RPM Transmissive delay : GO based calculation Incident point : Exit point : Estimated delay :

Estimated permittivity:

Propagation PathTrueRPM+Envelope

0 1 2 3 4 50

1

2

3

4

5

x/

z/

x/

y/

Target

Dielectric medium

Creeping wave: Must be suppressed for accurate permittivity estimation

同表面波の伝搬経路を推定

 

Eliminating the range points satisfying under condition

Estimated propagation delay of creeping wave:

：Outer boundary of dielectric object (Estimated by Envelope method)Internal image by RPM

Internal image estimation : Extended RPM・Boundary extraction using range point (time delay)・GO approximation

M

,M,M 12

2

,M,M,M,M,M,M

MM

2exp,maxarg

ˆ

N

k X

kikijk

,i

XXfs

ij qqrq

qr

qr

2

2

,M',M,M,M'1

,M,M,M2

minexp, 'S

r

kjijNj

kijf

qrqrqqr

Estimated internal point:

Permittivity estimation : Combination with GO and FDTD

Error caused by GO approx.: Compensated by FDTD method (Waveform Compensation: WC)

表面波距離0 2 4 6 8 10

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

R/

Real partAbsolute value

Creeping

Transmissive

Advantage : No need for a priori knowledge of dielectric object shape or location

1.5 2 2.5 3 3.5 41.5

2

2.5

3

3.5

4

x/

z/

Outer boundary by EnvelopeTrue boundary

2.4 2.6 2.8 32.4

2.6

2.8

3

x/

z/

Inner boundary before WCInner boundary after WC (WC: Waveform Compensation)

Estimated outer and inner boundaries Expanded view