本論文首先研究超寬頻訊號在車輛內的傳播，特別是車輛引擎蓋下方的環境。由於汽車環境中含有很多複雜的金屬結構，傳統窄頻通訊的傳輸品質對於發射器與接收器所在位置可能相當敏感，本研究透過實際量測與使用高頻數值電磁軟體模擬工具，來檢測寬頻訊號與環境中障礙物互相影響的狀況。在量測上，利用超寬頻單極天線，以涵蓋2~6 GHz的頻率範圍。將兩支相同超寬頻單極天線放置在車輛引擎室與車內各個位置，並使用網路分析儀紀錄在一寬頻範圍(2~6 GHz)的掃頻傳輸大小與相位。透過傅立葉轉換，將頻譜轉換為時域結果，以檢視傳播環境的特徵。除了車輛實測，本研究亦建置控制下的金屬障礙物模型，經由調整傳播障礙物模型環境的設置，可以辨識出主要散射源的位置。最後，應用高頻數值模擬軟體，進一步分析環境中的傳播特性，並瞭解障礙物各項傳播機制之貢獻程度。
在另一方面，由於無線通訊中的手持式設備增加，微型天線需求變大。利用傳統之遠場與近場量測系統來量測小型天線效率，不是很方便、且昂貴費時。因此本論文利用回聲實驗室做天線效率評估，開發出兩版回聲實驗室。在裡面放置收發天線，改變各種環境設定，以分析回聲實驗室的特性，並瞭解設計回聲實驗室時所需注意的地方。在量測上，利用網路分析儀掃瞄頻率，採取一邊攪拌電場，一邊利用網路分析儀平均的測量方式，以省去同步測量的機制，花費幾十秒即可讓傳播值收斂。最後，本論文使用已知效率的參考天線與待測天線比對在回聲實驗室的傳播係數，估計待測天線的輻射效率。從天線效率的實際量測與計算比對結果中，顯示我們所開發的回聲實驗室對於低指向性的天線可提供準確的效率估算。總的來說，本回聲實驗室適合量測窄頻且指向性低的天線效率，具有簡易經濟又快速的優點。

This thesis first investigates the propagation of ultra wideband signal in automotive environment, especially the car underhood. Because automotive environments contain many complicatedly metallic structures, the quality of conventional narrow band communication may be sensitive to the locations of transmitters and receivers. This study examines the interaction between broadband signals and obstacles in the propagation environment by means of measurements as well as simulations using a high frequency numerical electromagnetic tool. As to the measurements, the ultra wideband monopole antenna is used to cover the frequency range from 2 to 6 GHz. Two ultra wideband monopole antennas are placed at various locations in the car underhood. Transmission magnitudes and phases are recorded with a network analyzer. By applying the Fourier transform, the frequency spectrum is converted into time domain to exam the propagation characteristics of the environment. In addition to real car measurements, metallic obstacle models are built to examine propagation properties in a controlled environment. With adjustments in the propagation environment setup, the locations of primary scatters can be identified. Finally, a high frequency numerical simulation tool is applied to simulate the propagation environment and to reveal the contribution of each propagation mechanism.
On the other hand, due to the growing popularity of personnel mobile communication devices, miniaturized antenna designs are in great demands. It is expensive and time consuming to evaluate the small antenna performance using a traditional far field chamber. Therefore, this thesis attempts to develop reverberation chambers to evaluate antenna’s efficiency. Transmitting and receiving antennas are placed in various environmental setups to analyze the reverberation chamber characteristics. In measurements, a network analyzer is used to sweep a broad frequency band. Multiple measurements of various stirrer positions are averaged to achieve a converged transmission level, and the convergence is in general achieved in tens of seconds. The antenna efficiency is estimated by comparing the measured transmission level of the AUT antenna with the one from a known reference antenna. According to measurement and calculation results, the antenna efficiency estimation is more accurate for less directive antennas. The reverberation chamber proposed in this paper is suitable for efficiency estimation of narrow band and omni-directional antennas. The method is relatively simple, economic and fast.

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