Developements in next-generation advanced communication systems and devices have triggered multi-antenna systems for improved data throughput and transmission reliability. According to Shannon's theorem, to improve the channel capacity of a communication system, one method is to broaden the system bandwidth. Another method is to use the multiple-input-multiple-output (MIMO) technology. This technology uses multiple antennas at both transmitter and receiver to improve the channel capacity by several folds. Therefore, compact and broadband multi-antenna systems are very promising for future high-capacity wireless communication systems. / In parallel to advances in MIMO technologies, there is an irreversible trend that more and more communication protocols together with their respective antennas and radio transceivers are integrated into one compact unit. The radio systems of different protocols may work in very closely adjacent frequency bands or even overlapped bands. The coexistence of these multiple antennas has also become a concern from both industry and academic communities. / However, since the number of antenna elements is increasing in more and more compact devices, the physical limitation on inter-element spacing cannot be easily transcended, which will lead to destructive mutual coupling interference as well as pattern/spatial dependent correlation. In a multi-antenna system, the signals at all antenna ports are coded differently either to increase the packet rate or simply because that they belong to different radio transceivers. If unwanted signals are coupled to the ports, the signal-to-noise ratio will be deteriorated. Furthermore, the far-field patterns of closely spaced antennas are highly correlated and the signal envelope correlation will become significantly large. All these negative impacts will greatly diminish the channel capacity and the data throughput. Such drawbacks restrain the use of multiple antenna systems. It is therefore vital to develop a simple, broadband and effective decoupling technique for compact multiple antenna systems/arrays in advanced communication systems. / The major objectives of this thesis are (1) to innovate a new antenna decoupling technique called shunt type of coupled resonator decoupling networks (S-CRDNs) for wireless mobile terminal antennas; (2) to develop the synthesis theory and the design methodologies of the shunt type of CRDNs (S-CRDN) for various of antenna arrays; (3) to extend the theory and the design concept to dual band S-CRDNs, three port S-CRDNs and a LTCC S-CRDN module for mobile terminal applications; (4) to develop a cascaded type of coupled resonator decoupling networks (C-CRDN) for base station and wireless routers antennas; (5) to innovate a novel decoupling technique for multiple element antenna arrays with dummy antennas arrays; and more importantly, (6) to explore innovative applications with experimentally verified superiority. / Based on the characteristics of the coupled antennas, the synthesis theory of S-CRDNs starts from a set of required admittance polynomials, the targeted coupling matrix can be obtained from the polynomials analytically for a second-order S-CRDN. Possible coupling topologies of S-CRDNs include, but not limited to, a second-order all pole S-CRDN, a second-order S-CRDN with source-load coupling, a high-order S-CRDN network for dual band applications and a three port S-CRDN for three-element antenna arrays. Moreover, the concept of a “one-fit-all” S-CRDN module base on LTCC technology is also proposed and investigated, which makes an integrated S-CRDN module antenna independent as long as the frequency range matches. / The general theory of C-CRDN is developed in this thesis based on the circuit model of a 4-port coupled resonators network, which is proposed to solve the antenna decoupling problem between two base station antennas, to which a high level of isolation between two adjacent frequency bands is required, for the first time. This type of CRDN is particularly useful when one antenna transmitting very high power energy in a vicinity to a receiver antenna that works in an adjacent frequency band with very high sensitivity. / A decoupling technique with appropriately designed dummy elements and their passive complex loading is also proposed in this thesis. The technique employs the characteristics of non-radiating antenna elements (dummy elements). Multiple dummy elements can be introduced to alter the mutual coupling characteristic the radiating antennas in the original compact array. Therefore, this technique is more suitable for decoupling problem of an array with multiple elements. It is demonstrated that for a four-element compact array, four dummy elements are sufficient to decouple the four radiating elements in a broadband sense. Additionally, each radiating element can be independently matched. This decoupling technique can be extended to antenna arrays with a high number of radiating elements. / Finally, necessary and important figures of merit for benchmarking a multiple element antenna array are introduced. Prototypes of multi-antenna systems with and without using proposed decoupling techniques are fabricated, measured and compared. A large number of experimental results have demonstrated the superiority and the significance of the proposed decoupling techniques for compact antenna arrays of advanced wireless communication systems. / 下一代無線通訊系統與設備的飛速發展，極大的促進了多天線系統的開發與應用。多天線系統天生具有高數據吞吐率，并能夠確保傳輸的穩定性。根據香農定律，若想要提高一個系統的信道容量，要麼可以展寬系統帶寬，要麼可以適用多輸入多輸出（MIMO）系統。MIMO技術在發射端和接收端安置多個天線，以同時發送多路數據，大大提高了數據的吞吐率和信道容量。理想的狀態下，信道容量隨著收發天線的個數可以線性成倍增加。因此，新一代的小型化多天線系統正在成為未來發展的趨勢。 / 與此同時，現今無線通訊系統的發展趨勢越來越朝著小型化，集成化以及多功能化發展。這就意味著，越來越多的通信協議及其收發機和天線，將會集成到一個越來越小的終端設備上。另外由於頻譜資源的稀缺，這些共同工作的系統的頻帶越來越寬，頻帶之間的距離也越來越近。這些多天線的共存問題，也日益成為學術界和工業界關心的焦點問題。 / 但是，當終端的尺寸越來越小，而天線的個數越來越多的時候，天線之間的物理距離這個瓶頸是無法逾越的。如此受限的距離，不但造成了天線之間的相互干擾較大，也造成了他們方向圖和信道的強相關。在多天線系統中，各個天線處的信號編碼是不同的（包括提高數據速率和提高通信可靠性兩種不同的模式）。如果無用的信號耦合到了不該到的端口或者天線處，就會極大的影響信噪比和通信質量。另外，如果多天線的方向圖和信道是相關的話，信號的包絡相關性就會變得異常的大。這些都是嚴重影響多天線系統的性能的因素。因此，設計一種簡單的，寬帶的，有效的解耦技術，對於多天線系統是至關重要的。 / 本論文的主要目標是：（1）開發一種新的天線解耦技術，叫做並聯型耦合諧振腔解耦網絡，專門針對手機終端。（2）研究針對此解耦網絡的綜合設計手段，以針對不同的多天線陣列，都能有效的設計。（3）將此技術推廣到雙頻，多頻，多端口的多天線系統中。并研究利用低溫共燒陶瓷技術實現此類器件的小型化。（4）開發另一種級聯型耦合諧振腔解耦網絡，專門針對基站和路由器應用。（5）開發一種利用“假”天線進行解耦的新型技術。更重要的是（6）在實際使用場景中驗證所提出的各種解耦技術的有效性。 / 並聯型耦合諧振腔解耦網絡的綜合方法，需要受限根據耦合天線的特性和參數，得到一組電抗多項式，對於二階的網絡，所需要的耦合係數可以有這些多項式解析得到。實際上，並聯型耦合諧振腔解耦網絡的拓撲結構是多樣的，其中包括：兩階無交叉耦合型，兩階有交叉耦合及源負載耦合型，高階針對多頻的網絡以及三端口的網絡，專門針對三單元天線陣列。從並聯型耦合諧振腔解耦網絡，可以衍生出一種非常重要的基於低溫共燒陶瓷技術的“全能型”解耦網絡。這種網絡在頻率確定的情況下，可以適應各種不同的天線形式和耦合，非常適合在手機終端上廣泛採用。 / 本論文還討論了針對級聯型耦合諧振腔解耦網路的一般理論，以及其對應的電路模型和網絡參數。這種類型的網絡非常適合解決需要極高隔離度的基站天線解耦問題。這種網絡在本文中是業界首次提出的針對發射天線對領進頻帶接收機強幹擾的微波無緣網絡解決方案。 / 另外，一種採用“假”天線配合其電抗負載進行解耦的方法也將在文中提到。這種技術利用了並不輻射的“假”天線的寄生特性，通過引入若干不同空間排布的假天線陣，來解決原有天線陣的強互耦問題。這種方法的優越性是可以針對多種不同單元數和不同陣列排布的陣列。 / 最後，本文將會一一討論多種評估多天線系統性能指標的參數。包括隔離度，效率，包絡相關性，信道容量乃至吞吐率。作為比較，多種多天線系統，包括採用解耦網絡技術和不採用解耦網路技術的天線陣的各種性能參數，都在文中做了詳細比較。大量的實驗證明了採用解耦網絡的多天線系統的優越性。 / Zhao, Luyu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references. / Abstracts also in Chinese. / Title from PDF title page (viewed on 26, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_1290678 |
| Date | January 2014 |
| Contributors | Zhao, Luyu (author.), Wu, Ke-Li , 1959- (thesis advisor.), Chinese University of Hong Kong Graduate School. Division of Electronic Engineering. (degree granting institution.) |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography, text |
| Format | electronic resource, electronic resource, remote, 1 online resource (xxiii, 233 leaves) : illustrations (some color), computer, online resource |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons "Attribution-NonCommercial-NoDerivatives 4.0 International" License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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