以正交調變器為移相器?之陣列天線波束掃描系統

Abstract

本論文以正交調變器(Quadrature Modulator)為基礎，利用其基本原理推導出具有IQ移相器的特性，再設計了一組驗證電路來驗證理論推導，證實了正交調變器的相位和輸出能量的確是和輸入電壓有關係，而且是符合理論推導的公式，最後以此正交調變器為主，搭配一組四個單位天線的陣列，設計一個具有波束掃描功能的天線系統，此系統的操作頻率是在2.45GHz，並以LabVIEW程式控制類比訊號輸出卡(Analog output card)，輸出電壓來控制正交調變器的相位和能量變化。實驗結果顯示，本系統確實能達到波束掃描的功能，若是搭配更精密的電路和儀器來控制並掌握輸出能量和相位的話，我們就可以確實輸出所需要的波形，屆時將可以應用在智慧型天線上。

In the thesis, quadrature modulator-based phase shifter is employed for beam-steering of an antenna array system. We design a circuit to verify the theoretical derivation, and confirm that quadrature modulator's output phase and power is related to control voltage, and confirm the formula derived from quadrature modulator's theory. According to the theory we discussed, we design a quadrature modulator-based beam-steering system which use the patch array antenna with four units. The operating frequency of this system is 2.45GHz. LabVIEW is used to operate an analog-output card PCI-1724U for controlling the voltage that can change IQ quadrature modulator's output phase and power. The measured results show that the system achieves desired beam-steering function and agree with the simulation results very well. If we have a more sophisticated control circuit and equipment for controlling the quadrature modulator's output phase and power, we can steer the antenna main beam we want, and then apply it to a smart antenna system.