60GHz微帶線饋入圓極化微帶天線

Abstract

本論文中，我們主要是提出一種用微帶線饋入的圓極化微帶天線，經由模態分析法加以分析。首先將針對各式圓極化微帶天線進行介紹。 理論分析以共振腔模型為基礎，求解圓形微帶天線在共振腔中的模態。由模態分析的結果，可推導出在共振腔金屬面上的電流分布情形。而在本論文中是採直接饋入圓形微帶天線，但爲了增加頻寬和極化程度，經由結合循序旋轉的設計技巧，在此設計了微帶線饋入之圓形極化微帶線天線陣列。從模擬與量測結果當中，我們可以明顯的發現使用循序旋轉的技巧的 1x2 陣列天線，在頻寬上有明顯的提升。 由於本論文中所提出的天線是由微帶線所饋入，因此本身具有結構簡單，輕薄短小， 低姿態，易於與電路結合且製造的好處，故這些天線適合應用於高頻(毫米波)頻段。

In this thesis, a circularly polarized patch antenna fed by a microstrip-line is designed for the 60GHz (V-Band) communication system. In order to increase the bandwidth and polarization purity, a wide bandwidth microstrip-line fed circularly polarized patch array is proposed by combining the principle of sequential rotation technique and the 90° phase delay line for spatial rotation. Based on the cavity model, the Helmholtz’s equation is solved to obtain the modes exist in the circular cavity resonator. From the mode analysis results, the electric current distribution patterns on the patch and the ground plane are computed. Because we need increase the bandwidth and the polarization purity, a microstrip-line fed circularly polarized patch array is proposed by employing the principle of sequential rotation technique. The simulated and measured return losses are presented for an 1x2 array with and without sequential rotation technique. Significant increase in the return loss bandwidth is found in the array with sequential rotation. Because the proposed antenna is fed by the microstrip-line, in addition to the advantages of simple structure, lightweight, low profile, easy to combine with the circuit, and fabricate, this antenna is especially suitable for millimeter-wave application.