V頻段天線輻射場型量測

Abstract

本論文主要在於量測V頻段各式天線輻射場型，由於操作頻率較高可以縮短量測距離，因此試著建立一開放式小空間量測環境，以去除無反射室之量測環境需要。藉由矩形開口波導以及角錐形號角天線遠場輻射原理，推導輻射場型公式，再使用模擬程式分析，並與量測結果相比較，藉此判斷此量測環境之動態範圍與雜訊影響，設法得到正確之量測結果。在儀器控制上係撰寫電腦程式，建立一自動化量測之人機介面，藉由轉動待測天線，可即時顯示量測圖形並儲存資料，操作上則提供對話功能，讓使用者方便使用。為了得到精確之量測結果，設定向量網路分析儀在同一量測中，截取多個資料，經由做平均運算以降低雜訊影響，此外藉由程式內部設定變動臨界值，判別此平均值之變動，係由於待測天線在轉動過程中，造成之場型變化，還是雜訊產生之擾動。除了對角錐型號角天線之討論外，並敘述一由4×4巴特勒矩陣與微帶天線陣列，所構成之四波束切換式微帶天線陣列，分別比較其模擬和量測結果。

In this thesis, the radiation patterns of various V-band antennas are measured. Due to the higher operating frequency, a small open site for measuring the antenna radiation pattern is developed to give a cost-effective measurement environment. Starting from vector potentials, the far-field radiation pattern formulas of rectangular open-ended waveguide and pyramidal horn antenna are described. Measurement results verified by the simulation results are conducted by properly considering the dynamic range and noise effects of the measurement environment. On the instrument control, a man-machine interface of automatic measurement is written in Visual Basic language to control the test antenna position and record/display/store the measured data. In order to acquire accurate results, the vector network analyzer is set to average over a hundred readings for each measurement data; furthermore, the test antenna rotation is set to be adaptive to the variation of the averaged reading in order to effectively reduce the random noise in the measurement. Beside the pyramidal horn antennas, a four-element switched-beam patch antenna array by integrating a 4×4 butler matrix and an array of patch antennas, is measured in comparison with the simulation results using the developed measurement facilities.