The Journal of Korean Institute of Electromagnetic Engineering and Science (한국전자파학회논문지)

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
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Accuracy Examination in the RCS Computation of a Leaf Using the Resistive Sheet Technique with Various Thicknesses and Moisture Contents

잎 두께와 수분함유량에 따른 손실판 방식 RCS 계산의 정확성 검증

  • Park, Minseo (Department of Electronic Information and Communication Engineering, Hongik University) ;
  • Kim, Han-Joong (Department of Electronic Information and Communication Engineering, Hongik University) ;
  • Um, Kwiseob (Department of Electronic Information and Communication Engineering, Hongik University) ;
  • Park, Sin-Myong (Department of Electronic Information and Communication Engineering, Hongik University) ;
  • Kweon, Soon-Koo (LIG Nex1) ;
  • Oh, Yisok (Department of Electronic Information and Communication Engineering, Hongik University)
  • 박민서 (홍익대학교 전자통신정보공학과) ;
  • 김한중 (홍익대학교 전자통신정보공학과) ;
  • 엄귀섭 (홍익대학교 전자통신정보공학과) ;
  • 박신명 (홍익대학교 전자통신정보공학과) ;
  • 권순구 (LIG 넥스원(주)) ;
  • 오이석 (홍익대학교 전자통신정보공학과)
  • Received : 2014.07.01
  • Accepted : 2014.09.25
  • Published : 2014.11.30
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Abstract

The accuracy of the resistive-sheet technique in calculating the RCS(Radar Cross Section) of a deciduous leaf is examined in this paper for various thicknesses and dielectric constants, and a range of thicknesses for the resistive sheet technique is proposed. At first, a leaf was assumed to be a lossy dielectric disk, and the dielectric disk was again assumed to be a resistive sheet with an appropriate resistivity for a given thickness, a dielectric constant, and a frequency. Then, the RCS of the leaf was computed using the physical optics(PO) method, and was compared with the calculation results of a numerical analysis: i.e., a commercial tool based on the FEM (Finite Element Method) technique. It was shown that the error increases as the thickness increases. The error was 0.1 dB, for example, when the thickness is 1.2 mm and 3.7 dB when the thickness is 3 mm with a dielectric constant of(21.4, 9.7) at 9.6 GHz. It was also found that the error decreases as the dielectric constant increases. This study will be very useful for calculating the scattering characteristics of numerous leaves in a vegetation canopy for estimating its radar backscatter using scattering model.

본 논문에서는 손실판(resistive sheet) 방식을 사용하여 풀잎이나 나뭇잎의 후방 산란 레이더 단면적(RCS: Radar Cross Section)을 계산하고, 이 모델의 정확성을 검증하여, 손실판 모델을 적용하여 계산 가능한 잎의 두께를 제시한다. 이를 위해 잎을 손실 있는 유전체 판으로 가정하고, 이 유전체 판을 resistive sheet(손실판)으로 대체한 후에 판의 두께, 유전율, 주파수에 따른 resistivity를 계산한 후에, PO(Physical Optics) 방식을 이용하여 다양한 크기와 두께 조건에서 RCS를 계산하였고, 이 계산 결과를 상용 시뮬레이터를 사용한 FEM(Finite Element Method) 방식의 수치해석 계산 결과와 비교하였다. 이 비교 결과에 의하면 유전체 판의 두께가 커질수록 오차가 증가하였으며, 예를 들어, 주파수 9.6 GHz에서 유전율이 21.4+9.7i이고, 잎 두께가 1.2 mm일 때 0.1 dB의 오차가 발생하였고, 3 mm일 때 3.74 dB의 오차가 발생하였다. 또한, 유전율이 높아질수록 이 모델 사용 가능한 최대 두께가 증가하는 경향을 보였다. 이 연구는 원격탐사 연구에서 수많은 잎이 분포되어 있을 때에 그 잎들의 산란 특성을 산란모델을 이용하여 계산하는 데에 유용하게 사용될 것이다.

Keywords

References

  1. 곽영길, "위성 영상 레이다(SAR) 기술 동향", 한국전자파학회 전자파기술지, 22(6), pp. 4-16, 2011년 11월.
  2. A. Reigber, R. Scheiber, M. Jager, P. Prats, I. Hajnsek, T. Jagdhuber, K. Papathanassiou, M. Nannini, E. Aguilera, S. Baumgartner, R. Horn, A. Nottensteiner, and A. Moreira, "Very high-resolution airborne synthetic aperture radar imaging: Signal processing and application", Proc. IEEE, vol. 101, no. 3, pp. 759-783, Mar. 2013. https://doi.org/10.1109/JPROC.2012.2220511
  3. K. Sarabandi, T. B. Senior, and F. T. Ulaby, "Effect of curvature on the backscattering from a leaf", J. Electromagn. Waves Applicat., vol. 2, no. 7, pp. 653-670, 1988.
  4. M. A. Karam, A. K. Fung, "Leaf-shape effects in electromagnetic wave scattering from vegetation", IEEE Trans. Geosci. Rem. Sens., vol. 27, no. 6, pp. 687-697, Nov. 1989. https://doi.org/10.1109/TGRS.1989.1398241
  5. M. Kurum, R. H. Lang, P. E. O' Neill, A. T. Joseph, T. J. Jackson, and M. H. Cosh, "A first-order radiative transfer model for microwave radiometry of forest canopies at L-band", IEEE Trans. Geosci. Remote Sens., vol. 49, no. 9, pp. 3167-3179, Sep. 2011. https://doi.org/10.1109/TGRS.2010.2091139
  6. T. B. A. Senior, K. M. Sarabandi, and F. T. Ulaby, "Measuring and modelling the backscattering cross section of a leaf", Radio Sci., vol. 22, no. 6, pp. 1109-1116, Nov. 1987. https://doi.org/10.1029/RS022i006p01109
  7. M. A. Karam, A. K. Fung, and Y. M. M. Antar, "Electromagnetic wave scattering from some vegetation samples", IEEE Trans. Geosci. Remote Sensing, vol. 26, no. 6, pp. 799-808. Nov. 1988. https://doi.org/10.1109/36.7711
  8. M. A. El-Rayes, F. T. Ulaby, "Microwave dielectric spectrum of vegetation-Part I : Experimental observations", IEEE Trans. Geosci. Remote Sensing, vol. 25, no. 5, pp. 541-549, Sep. 1987.
  9. F. T. Ulaby, M. A. El-Rayes, "Microwave dielectric spectrum of vegetation-part II : Dual dispersion model", IEEE Trans. Geosci. Remote Sensing, vol. 25, no. 5, pp. 550-557, Sep. 1987.
  10. Y. Oh, J. Y. Hong, "Re-examination of analytical models for microwave scattering from deciduous leaves", IET Microw. Antennas Propag., vol. 1, no. 3, pp. 617-623, Jun. 2007. https://doi.org/10.1049/iet-map:20050081
  11. C. A. Balanis, Advanced Engineering Electromagnetics, John Wiley & Sons, pp. 311-345, 2011.
  12. R. F. Harrington, J. R. Mautz, "An impedance sheet approximation for thin dielectric shells", IEEE Trans. Antennas Propag., vol. 23, no. 4, pp. 531-534, Jul. 1975. https://doi.org/10.1109/TAP.1975.1141099
  13. T. B. A. Senior, "Combined resistive and conductive sheets", IEEE Trans. Antennas Propag., vol. 33, no. 5, pp. 577-579, May 1985. https://doi.org/10.1109/TAP.1985.1143616