金屬物體毫米波影像之研究

Study of millimeter wave imaging of conducting objects

魏健倫(Cheng-Lun Wei)

指導教授 ： 瞿大雄

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.01205

摘要

本論文主要係研究以毫米波照射金屬散射物體，由其後向掃描屏幕所得之散射場，重建金屬物體之毫米波影像。金屬物體之散射模擬，係以離散點表示金屬物體上之散射中心，並配合推導之成像公式，使用傅氏轉換重建散射物體之毫米波影像。
理論分析，首先描述散射金屬物體受平面波照射，經物理光學近似，推導於後向掃描屏幕上，所接收之散射場與散射物體之關係式，再經由合理近似假設，經由反傅式轉換得到物體之毫米波影像，因此可藉由適當控制頻率、距離及掃描屏幕尺寸，得到合理的散射物體的影像與影像解析度。論文中並針對不同散射體進行模擬，包含單點物體、多點物體、以及複雜形狀的飛機與手槍等散射物體，以探討散射物體與其成像之關係。

關鍵字

毫米波成像 ； 散射公式 ； 成像公式 ； 解析度

並列摘要

This thesis mainly describes the study of millimeter-wave imaging of conducting objects. Based on the scattered field recorded over a scanned aperture at the backward direction of the conducting object, Chapter 2 derives the formulation to reconstruct the millimeter-wave images of the scattering objects. In Chapter 3, the simulation of the object scattered field is conducted by using discrete points to represent the scattering centers over the conducting object, then uses Fourier transformation to reconstruct the millimeter-wave image of the scattering object.
In the theoretical analysis, the scattering conducting object is illuminated by a plane wave, under physical optics approximation, the relation between the scattering object and its scattered field over the backward scanned aperture is derived, and then under a reasonable approximation, millimeter-wave image of the scattering object can be reconstructed through two-dimensional inverse Fourier transformation. Therefore by properly controlling the frequency, distance and size of scanned aperture, one can acquire the reasonable quality and resolution of the scattering object image. In this thesis, simulations of different scattering objects, including single point object, multiple point object, as well as complex shaped airplane and pistol are conducted to study the relationship between the scattered field and the formation of image.

並列關鍵字

millimeter-wave image ； scattering formula ； imaging formula

參考文獻

[7] T. H. Chu, and N. H. Farhat, “Frequency-sweptmicrowave imaging of dielectric projects,” IEEE Trans. Microwave Theory Tech., vol. 36, pp. 489-493, Mar. 1988.

[8] N. H. Farhat, C. L. Werner, and T. H. Chu, “Prospects for three–dimensional projective and tomographic imaging radar networks,” Radio Sci., vol. 19, pp. 1347-1355, 1984.

[9] D. C. Munson, Jr., J. D. O'Brien, and W. K. Jenkins, “A tomographic formulation of spotlight-mode synthetic aperture radar, ” Proc. IEEE, vol. 71, pp. 917-925, Aug. 1983.

[10] C. K. Chan and N. H. Farhat, “Frequency swept tomographic imaging of three-dimensional perfectly conducting objects,” IEEE Trans. Antennas Propagat., vol. AP-29, pp. 312–319, Feb. 1981.

[11] W.-M. Boerner, C.-M. Ho, and B.-Y. Foo, “Use of Radon’s projection theory in electromagnetic inverse scattering,” IEEE Trans. Antennas Propagat., vol. AP-29, pp. 336–341, Feb. 1981.