運用基頻相移技術實現適應性雙通道波束成形器

Abstract

本論文利用基頻信號相位差控制高頻信號相位差的概念，設計具有電子式掃描功能的升頻電路系統，並利用被動式IQ混波器設計的相位偵測器與蕭基特二極體設計零偏壓功率偵測器的干涉儀偵測器，分別檢視與校正此升頻系統。經過理論推導與實驗證實低頻訊號相位差的變化經由升頻後亦可以控制高頻訊號相位差。此系統操作在亞洲地區LTE使用頻段2.60GHz，並搭配LabVIEW程式軟體控制整體系統的運作與資料處理，其中包含：基頻訊號的產生、量測相位讀取、量測功率讀取及數值運算。依據實驗結果顯示，本系統具有約60MHz頻寬，搭配高增益天線，將可應用於LTE基地台。

In this thesis, a two-way radio frequency (RF) beam-former is presented including the component characteristics and system performance. By electrically tuning the phase angles of the baseband continuous-wave signal generated by digital direct synthesizer (DDS) together with the up-converter, we can achieve a RF phase shifting scheme without exploiting the expensive RF phase shifters. Notably, the phase-angle deviation between the two RF output ports caused by the inhomogeneity of the dielectric substrate as well as the components degrades the performance of the beam-former. To resolve this problem, the two approaches for measuring the phase deviation are also taken into account, which are the IQ-mixer-based phase detector and power-combiner-based interferometer. The output RF phase angles can be adaptively and correctly generated by dynamically synthesizing the baseband signal patterns by incorporating the phase compensation. Such a digital beam-forming technique can be employed in the Long-Term Evolution (LTE) base-station architecture.