Far Field Target Image by Near Field RCS Measurement

• Main Authors: Min-Che Tsai, 蔡明哲
• Other Authors: Dau-Chryh Chang
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/28044811540626091178

碩士 === 大葉大學 === 電機工程研究所 === 90 === 　　The experiment in this paper is conducted with Electromagnetic Anechoic chamber, HP8722D (Vector Network Analyzer), and near field measurement system to recover the microwave image of the test target. In far field RCS (radar cross section area) measurement, there are weather and multipath problems during measuring. These problems can be resolved by measuring test target in near field range. This thesis provides methods to obtain a target far field radar cross section. The methods will include, (1)establishing the near field data for receive power decrease with distance to compensate the near field range power decay, (2)providing a way to obtain a target far field image, and (3)rotating the target with small angle used in ISAR (Inverse Synthetic Aperture Radar) to resolve the serious quadratic phase error which effect the defocus of the image. The result of down range prediction is agreed to that of GTD prediction. In the simulation cases, the signal to noise ratio for compensation images are greater than 20dB. In the experimental cases, the compensation images are all clear. Keyword: near field small rotating angle scan