| Summary: | 博士 === 國立交通大學 === 電子工程學系 === 85 === MST(VHF)雷達技術發展至今 , 已經由多方面研究所得可以證實 ,
VHF 雷達確實是一個非常有效之遙測工具 , 而且不斷的有新技術 , 新理
論被提出 . FDI (FrequencyDomain Interferometry ), 目的是要利用
VHF 雷達來作存在空氣中穩定層狀結構厚度的測量及其高度的定位 , 此
技術從提出 (Kudeki . E , 1987 ) , 接下來是一些學者 ,利用其理論來
作實際層狀結構觀測 , 但在 (Chu and Franke , 1991) 所作之大氣層狀
結構觀測時 , 發現了觀測之相干值和傳統理論之相干值不吻合(較理論相
干值高) , 進而我們對傳統理論作了波數功率頻譜 (Wavenumber Power
Spectrum )及有限之雷達積分(Finite Radar Volume Integration ) 二
項修正 , 其結果和觀測資料非常吻合 , 也就是利用傳統 FDI 理論來作
層狀結構厚度及位置的估算 , 將會產生誤估 , 修正後之結果推翻了傳統
理論 .
The frequency domain interferometry (FDI) technique , first
developed by Kudeki and Stitt (1987) , provides us with the
ability to detect such a thin layer by sending two closely
spaced frequencies with this technique , thethickness and the
position of the thin layer can be estimated , respectivelyfrom
the magnitude ( ie , coherence ) and phase of the normalized
complexcross-correlation function calculated from the two radar
retuns with slightly different operating frequencies , but
experiments have not been successfully .The frequency domain
interferometry (FDI) experiment (Chu and Steven , 1991 )have
been conducted successfully at various MST radar and the
thickness and position of the thin layer are estimated , by
considering the wavenumber power spectrum of the refractivity
irregularity and the limit of integration to be finite , it show
that the frequency domain interferometry (FDI) coherenceis not
only the function of layer thickness and the components of radar
wavevector but also considering the wavenumber power spectrum of
the refractivity irregularity and the limit of integration to be
finite.
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