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Practical Antenna Design for Mobile Terminal Applications
|Authors: ||Lin, Cheng-Hung|
|Contributors: ||NTOU:Department of Electrical Engineering|
Multi-bands antenna;Mobile antenna;Antenna measurement;Diversity antenna
|Issue Date: ||2018-08-22T07:11:54Z
|Abstract: ||近年來,隨著科技的進步和通訊系統的蓬勃發展，行動通訊產品成為生活中不可或缺的一部分，而通訊產品所使用的頻帶也日益增多。要在外型輕薄且尺寸微小的無線通訊產品中設計出多個天線，而且要考慮到天線元件間造成的相互耦合的所產生的影響。要如何為通訊產品設計寬頻及多頻的天線，並且提高資料傳輸速率和多通道容量的需求，成為在無線傳輸領域研究創新的主要重點。 本論文從考量系統設計的角度，將天線配置於行動通訊產品中，其中包括使用於GPS、BT、WLAN和Cellular phone的天線，研究並討論各個相對應的天線設計。一開始的天線設計，研究單極天線和貼片天線，設計出隱藏在產品內的天線，並藉由增加天線輻射體的彎折數與改變耦合的位置，達到縮小化與增加頻寬的目的，讓天線可以應用在多頻段。進一步的，研究設計輻射體的形狀結構，達到所需要的頻段和頻寬，應用在Cellular phone通訊系統上，並且研究分集天線和多工技術，設計操作於同一行動通訊產品內同頻段的多個天線。 本論文設計了可應用在2G / 3G /4G的多頻天線，天線設計達到所需要的頻率範圍。其中改變天線輻射體槽孔的耦合位置，來調整天線共振的阻抗和操作頻帶。在考慮真實的產品設計環境中，天線空間內配置其他的元件，而存在著對天線效能的影響。因此研究將串接介面連接器融入在天線的空間設計上，為了避免金屬連接器的影響，嘗試在電路上加入了分頻器，設計達到所需要的效能。最後，本論文用金屬飾板當作輻射體，整合主動式電路多工器與天線，保有全金屬背蓋的完整結構，設計出GSM、DCS、PCS、WCDMA和LTE多頻段的通訊天線。所提出的天線設計在電波暗室所量測的天線特性,顯示出適合應用於行動通訊產品。|
Mobile communication devices have become an important commodity of everyday life. The product trend is toward multi-functional applications and the communication system is developed to operate in multi-bands. Hence, the demands for broadband and multi-bands antenna design are ever increasing. Furthermore, increasing the data rate and channel capacity in modern wireless communication systems is also crucial for the product development. The technologies of diversity and MIMO antennas are applied to accommodate multiple data streams. Designing multiple antennas in a compact and low profile device is itself a great challenge and the difficulty is further accentuated by the need to consider the mutual coupling between the antenna elements. The work is intending toward internal antennas design instead which can be placed inside a mobile device. The built-in design facilitates easier miniaturization. The first study is utilizing monopole and patch antennas for multi-bands design. By increasing the meandered structure and changing the coupled position of the antenna radiator, the resonant frequencies and the bandwidths can be adjusted. The antenna design can be applied to dual-band for GPS and WLAN applications. In accordance with different communication system needs, the shape and structural design of the radiator were also studied to achieve the desired resonant frequencies and bandwidths for application in the second / third generation (2/3G) mobile communications system. Furthermore, diversity and MIMO technologies have also been considered in the design of the multiple antenna system. With the rising of the fourth generation (4G) technology, there are more bands required for the communication system. The study is then extended to design multi-bands antenna for the 2/3/4G applications. From the antenna design point of view, the added frequency which goes down to 700 MHz creates the main design challenge for covering 700 - 960 MHz in the low-band. Since the space reserved for the antenna is electrically small in this frequency range, special antenna design techniques are necessary to obtain the required bandwidth for mobile terminal. By adjusting the position of the slot over the antenna radiator, the desired antenna resonant frequencies and bandwidths were achieved. The antenna radiation characteristics were evaluated and measured in an anechoic chamber. The study also considered the real operation condition of the device, where metallic accessories elements are always in the vicinity of the antenna and affect the antenna efficiency. Hence, a USB connector is in place with the antenna. To mitigate the impact from the connector, a divider is implemented in the circuit of the antenna design for the performance testing. The proposed antennas characteristics are measured in an anechoic chamber. Our test showed that the current antenna design performed well. By using a metal nameplate of the device as a radiator and implemented active circuits, our measurements showed that the system can operate well in full metal casing structure and covered the multi-bands for GSM, DCS, PCS, WCDMA and LTE applications.
|Appears in Collections:||[電機工程學系] 博碩士論文|
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