以GPS進行點位量測時，觀測量是以天線相位中心為基準的，然而，天線相位中心並非天線之物理中心，且相位中心是非固定的。對於任一GPS天線，其相位中心會隨衛星信號來源方向而改變，因此，GPS天線相位中心變化是相當複雜的。另外，相位中心的變化與天線形式是相關的，此種變化在混合不同型式天線同步觀測時應仔細考量修正。不同型式天線之相位中心變化主要影響為GPS測站之相對高程，其影響可達10公分（不論測站之遠近）。即使使用同型天線，仍可能造成0.015ppm之尺度誤差。
GPS天線相位中心偏移量及變化量可由實驗室法及實測GPS觀測法分別測定。本研究將以實測GPS觀測法來率定相位中心偏移量及變化量，此方法較實驗室法簡易，而精度仍可達到實驗室法的水準，但所獲得者為天線間之相對改正量，因此，至少需有一部天線（參考基準）視為已知。
本研究將比較相位中心改正前後對GPS量測精度之影響，並建議一可行之GPS天線相位中心率定模式，及相位中心改正模式。

The precise point whose position is being measured from GPS is generally assumed to be the phase center of the GPS antenna. However, the phase center of a GPS antenna is neither a physical point nor a stable point. For any given GPS antenna, the phase center will change with the direction of the signal from a satellite. Therefore, the variation of the GPS antenna phase center is very complicated. Besides, the phase center variations are antenna-type-dependent. This effect has to be carefully modified when different types of antennas are used simultaneously. Ignoring these phase center variations can lead to serious (up to 10 cm) vertical errors that are independent on the baseline length. Even if the same types of antennas are used, the main effect is a scale factor up to about 0.015ppm.
The antenna phase center offsets and it’s variations may stem either from anechoic chamber measurements or from estimations using GPS data. This study will estimate the antenna phase center offsets and variations from GPS data. The effort for setting up such a campaign is considerably smaller than collecting the chamber measurements. The resulting accuracy is comparable with that of the chamber tests but the disadvantage is that only the relative corrections may be estimated. Therefore at least one reference antenna has to be introduced as known.
We will compare the results of GPS measurements from phase center corrections and no corrections. And command a feasible method to calibrate antenna phase center and a correction model.

中文摘要 ………………………………………………….. i
英文摘要 …………………………………………………. ii
目錄 ……………………………………………………… iii
表目錄 ……………………………………………………. v
圖目錄 …………………………………………………… vi
第一章 前言……………………………………………… 1
1-1 研究動機與目的 .……………………………………... 1
1-2 研究方法 ……………………………………………… 2
1-3 研究內容 ……………………………………………… 3
第二章 GPS接收儀天線相位中心特性 ..………………….. 4
2-1 GPS天線基本類型及特性 ...…………………………… 4
2-1-1 GPS天線的原理及基本要求 ..…………………… 4
2-1-2 GPS 天線型式 ..…………………………………... 5
2-2 GPS天線相位中心變化 ….…………………………….. 7
2-3 相位中心變化所造成之影響 …………………………. 10
第三章 相位中心變化的率定方法及理論 …………….. 14
3-1 率定值之自由度 ………………………………………... 14
3-2 實驗室法 ………………………………………………... 15
3-3 實測GPS觀測法率定相位中心變化…………………… 16
3-3-1 實測GPS觀測法之概觀與背景介紹 ………… 16
3-3-2 實測GPS觀測法之求定理論說明 …………… 17
3-4 實驗室法與實測GPS觀測法之比較 …………………. 19
第四章 實驗說明及資料處理 ………………………………. 20
4-1 實驗步驟說明 …………………………………………... 20
4-2 試驗相關說明 …………………………………………... 21
4-2-1 試驗天線相關資料 ……………………………... 21
4-2-2 試驗天線整置 …………………………………... 24
4-3 資料處理 ……………………………………………….. 30
4-3-1 Bernese 4.0 版軟體介紹及計算流程 …………... 30
4-3-2 GPS數據處理採用模式 ………………………… 32
4-3-3 以Bernese軟體計算天線相位中心偏移量
及變化量相關說明 ……………………………… 33
第五章 研究成果及分析 …………………………………….. 38
5-1 相位中心偏移量率定結果 ……………………………... 38
5-2 相位中心變化量率定結果 ……………………………... 43
5-3 實驗成果之分析比較 …………………………………... 50
5-4 GPS天線相位中心改正於GPS量測之影響 …………… 55
第六章 結論與建議 …………………………………………... 69
參考文獻 ………………………………………………………… 71
附錄A 各觀測天相位中心偏移量率定結果 …………….. 74
附錄B 各觀測天相位中心變化量率定結果 …………….. 77
附錄C 各觀測天相位中心改正前後座標偏移量 ………. 87

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