- 學位論文
應用於毫米波頻段之陣列天線模組化設計
Antenna-in-Module (AiM) Design for Applications in Millimeter-Wave Band
摘要
本論文主要為提出數個毫米波主動式陣列天線的設計方式與特性分析，藉由分析各式射頻主動元件的特性後，以模組化整合的設計方式將陣列天線與射頻主動元件相結合，達成一緊密的主動式陣列天線模組化架構。本論文共提出了四種操作在毫米波頻段的天線模組設計，並皆以微帶天線作為各天線單元的原型。此論文首先提出了數個微帶天線在多層板製程中增加頻寬的方式，隨後提出了一抑制次極化程度(cross-polarization level)的並聯饋入設計，這些性能提升之理論都會在全波模擬軟體內進行驗證。 本論文中四種天線模組共包含6×6單極化主動陣列天線、8×8單極化主動陣列天線、8×8雙極化主動陣列天線以及32×32單極化主動陣列天線。6×6單極化主動陣列天線基於既有的34×34 mm2 PCB尺寸限制，將天線以28GHz的半波長作等間距排列，該天線模組藉由使用非常規天線單元數量及晶片排列方式，實現了以最小的體積下達到最大化的天線數量。8×8單極化主動陣列天線以傳統的天線排列方式，在水平方向以28GHz的0.5波長、垂直方向以28GHz的0.7波長作等間距排列，實現目前應用上最常見的天線設計架構；在相同天線單元下也將其功能擴展至雙極化，並以理論的方式探討如何動態地改變極化方向以最大化天線接收訊號強度，在此設計中還使用了多一倍的晶片單元使天線在兩個極化方向及兩個切面都呈現鏡像饋入，使天線整體的次極化程度大幅改善。32×32單極化主動式陣列天線主要由8×8單極化陣列擴展成16組8×8的子陣列(sub-array)，而每一組子陣列天線都有一獨立的RF輸出(入)端口，故每一組子陣列都可以同時擁有自己波束偏移方向，並可以同時收(發)多組訊號，達到MIMO系統的運作情境。 為驗證所提出之天線模組進行通訊測試，本論文自行設計一自帶鎖相迴路系統之升降頻模組，藉由將訊號從不同升降頻模式之輸入(出)進行調整，分析升降頻模組整體的特性，最後搭配SDR(Software Defined Radio, SDR)的系統平台，將此數位訊號進行數學運算達到在空間上天線彼此間的通訊傳輸。
並列摘要
This paper presents the design methodologies and characteristics analysis of millimeter-wave active array antennas. The array antennas are integrated with RF active components in system integration level after analyzing the performance of various RF active components, achieving a compact modular active array antenna architecture. Four antenna modules which operating in the millimeter-wave frequency are proposed in this paper, with microstrip antennas acting as the prototypes for antenna unit. At the first, a concept is proposed to increase the bandwidth of microstrip antennas in a multilayer process and then introduces a parallel feeding network design to suppress the cross-polarization level of antenna. The theoretical enhancements in performance will be validated by using full-wave simulation software. In this paper, four antenna modules are presented, including a 6×6 single-polarized, an 8×8 single-polarized, an 8×8 dual-polarized and a 32×32 single-polarized active array antenna. The 6×6 array module is limited by the existing 34×34 mm2 PCB size constraint. These antenna units are arranged at a distance of half wavelength at 28 GHz from each other. By adopting an unconventional number of antenna elements and chip placing distribution, this module can achieve the optimal performance in using the minimum volume. The 8×8 single-polarized array module adopts a traditional antenna arrangement, with equal spacing in the horizontal direction based on a 0.5 wavelength at 28 GHz and in the vertical direction based on a 0.7 wavelength at 28 GHz. This design is the most common antenna archieture used in applications. Additionally, this design is transformed to dual polarization by using more beamforming chip, which means there are more antenna feed channel to excite another orthogonal mode. The twice number of chip are used to enable mirror feeding network on two planes in two polarization, respectively, which significantly improve the overall cross polarization level. The 32×32 single-polarized array module is primarily an expansion of the 8×8 array into 16 sets of it subarrays. Each subarray has an independent RF output/input port, allowing it to have its own beam steering direction. As a result, each subarray can simultaneously transmit/receive multiple signal to achieve a possible scenario for MIMO systems. In order to validate the proposed antenna modules in communication applications, an up/donw converter with phase-locked loop circuit is designed. The caracteristics of the up/down converter module is analyzed by adjusting the input/output signals in different conversion modes. At last, the communication transmission between the anrenna in space is completed by integrating a software defined radio (SDR) system with up/down converter.