c R/ Output of matched filter at R2 (Reflection echo) c R/ Output of matched filter at R1 (Transmissive echo) -1 0 1 1 1.5 2 2.5 3 3.5 4 x/ z/ Permittivity and Internal Image Estimation Accurate Image Expansion Method for Target Buried in Dielectric Medium Using Multi-static UWB Radar Toshiki Manaka 1 , Shouhei Kidera 2 and Tetsuo Kirimoto 2 1 Graduate School of Bioengineering, The University of Tokyo, Japan 2 Graduate School of Informatics and Engineering, The University of Electro-Communications, Japan Email: [email protected] RMSE[λ] Estimated permittivity Relative error of permittivity [%] Before WC 5.83×10 -2 8.56 5.6 After WC 3.90×10 -2 8.84 2.8 Microwave UWB Radar ・Non-invasive bio-imaging ・Non-destructive testing for detecting crack of wall General 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 echo R2: 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 Path True RPM+Envelope 0 1 2 3 4 5 0 1 2 3 4 5 x/ z/ ோଶ ଵ ௧ ௧ x/ y/ ோଶ ଵ Target Dielectric medium େ େ େ Creeping wave: Must be suppressed for accurate permittivity estimation మ భ 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 1 2 2 , M , M , M , M , M , M M M 2 exp , max arg ˆ N k X k i k i j k ,i X X f s i j q q r q q r q r 2 2 , M ' , M , M , M ' 1 , M , M , M 2 min exp , ' S r k j i j N j k i j f q r q r q q r Estimated internal point: Permittivity estimation : Combination with GO and FDTD Error caused by GO approx. : Compensated by FDTD method (Waveform Compensation: WC) 0 2 4 6 8 10 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 R/ Real part Absolute value Creeping Transmissive Advantage : No need for a priori knowledge of dielectric object shape or location 1.5 2 2.5 3 3.5 4 1.5 2 2.5 3 3.5 4 x/ z/ Outer boundary by Envelope True boundary 2.4 2.6 2.8 3 2.4 2.6 2.8 3 x/ z/ Inner boundary before WC Inner boundary after WC (WC: Waveform Compensation) Estimated outer and inner boundaries Expanded view